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                                                                       EXHIBIT 1


                         Northern Border Partners, L.P.

                                    4,455,218
                                Common Units(1)
                     Representing Limited Partner Interests

                             Underwriting Agreement


                                                              New York, New York
                                                                    May 16, 2001


Salomon Smith Barney Inc.
Banc of America Securities LLC
UBS Warburg LLC
A.G. Edwards & Sons, Inc.
Dain Rauscher Incorporated
First Union Securities, Inc.
as Representatives of the several Underwriters,
c/o Salomon Smith Barney Inc.
388 Greenwich Street
New York, New York 10013


Ladies and Gentlemen:

         Northern Border Partners, L.P., a limited partnership organized under
the laws of Delaware (the "Partnership"), proposes to sell to the several
underwriters named in Schedule I hereto (the "Underwriters"), for whom you (the
"Representatives") are acting as representatives, 4,000,000 Common Units
("Common Units") of the Partnership, and the person named in Schedule II hereto
(the "Selling Unitholder") proposes to sell to the several Underwriters 455,218
Common Units (said units to be issued and sold by the Partnership and units to
be sold by the Selling Unitholder collectively being hereinafter called the
"Underwritten Securities"). The Selling Unitholder named in Schedule II hereto
also proposes to grant to the Underwriters an option to purchase up to 668,282
additional Common Units to cover over-allotments (the "Option Securities"; the
Option Securities, together with the Underwritten Securities, being hereinafter
called the "Securities"). To the extent there are no additional Underwriters
listed on Schedule I other than you, the term Representatives as used herein
shall mean you, as Underwriters, and the terms Representatives and Underwriters
shall mean either the singular or plural as the context requires. The use of the
neuter in this Agreement shall include the feminine and masculine wherever
appropriate. Any reference herein to the Registration Statements, a

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(1)  Plus an option to purchase from the Selling Unitholder up to 668,282
     additional Securities to cover over-allotments.

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Preliminary Prospectus or the Prospectus shall be deemed to refer to and include
the documents incorporated by reference therein pursuant to Item 12 of Form S-3
which were filed under the Exchange Act on or before the respective Effective
Dates of each of the Registration Statements or the issue date of such
Preliminary Prospectus or the Prospectus, as the case may be; and any reference
herein to the terms "amend", "amendment" or "supplement" with respect to any of
the Registration Statements, any Preliminary Prospectus or the Prospectus shall
be deemed to refer to and include the filing of any document under the Exchange
Act after the respective Effective Dates of each of the Registration Statements,
or the issue date of any Preliminary Prospectus or the Prospectus, as the case
may be, deemed to be incorporated therein by reference. Certain terms used
herein are defined in Section 17 hereof.

         1. Representations and Warranties.

         (i) The Partnership and Northern Border Intermediate Limited
Partnership, a Delaware limited partnership (the "Intermediate Partnership"),
jointly and severally represent and warrant to, and agree with, each Underwriter
as set forth below in this Section 1.

         (a) The Partnership has prepared and filed with the Commission three
     registration statements on Form S-3 (file numbers 333-40601, 333-72323 and
     333-72351), in each case including a related base prospectus subject to
     completion, for registration under the Act of certain securities of the
     Partnership, including the offering and sale of the Securities, each of
     such Registration Statements has been declared effective by the Commission,
     and no stop order suspending the effectiveness of any of the Registration
     Statements has been issued by the Commission. At the time of the filing of
     each such Registration Statement, the Partnership met the requirements for
     use of Form S-3 under the Act. The Partnership may have filed one or more
     amendments or supplements thereto, including a preliminary prospectus
     supplement which relates to each such base prospectus, each of which has
     previously been furnished to you. The Partnership will next file with the
     Commission a final prospectus supplement which relates to each such base
     prospectus, together with each such base prospectus, in accordance with
     Rules 430A and 424(b). The Partnership has included in each such
     Registration Statement, as amended and supplemented at its respective
     Effective Date or the issue date of the Prospectus, as applicable, all
     information (other than Rule 430A Information) required by the Act to be
     included in each such Registration Statement and the Prospectus. As filed,
     such final prospectus supplement together with each such base prospectus,
     shall contain all Rule 430A Information, together with all other such
     required information, and, except to the extent the Representatives shall
     agree in writing to a modification, shall be in all substantive respects in
     the form furnished to you prior to the Execution Time or, to the extent not
     completed at the Execution Time, shall contain only such specific
     additional information and other changes as the Partnership has advised
     you, prior to the Execution Time, will be included or made therein.

         (b) Each Registration Statement, on its respective Effective Date, did,
     and when the Prospectus is first filed in accordance with Rule 424(b) and
     on the Closing Date (as defined herein) and on any date on which Option
     Securities are purchased, if such date is not the Closing Date (a
     "settlement date"), the Prospectus (and any supplements thereto) will,
     comply in all material respects with the applicable requirements of the Act
     and the


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     Exchange Act; each Registration Statement, on its respective Effective
     Date, and each Registration Statement, as supplemented or amended, at the
     Execution Time, did not or will not contain any untrue statement of a
     material fact or omit to state any material fact required to be stated
     therein or necessary in order to make the statements therein not
     misleading; and on the date of filing pursuant to Rule 424(b) and on the
     Closing Date and any settlement date, the Prospectus (together with any
     supplement thereto) will not, include any untrue statement of a material
     fact or omit to state a material fact necessary in order to make the
     statements therein, in the light of the circumstances under which they were
     made, not misleading; provided, however, that the Partnership makes no
     representations or warranties as to the information contained in or omitted
     from any of the Registration Statements or the Prospectus (or any
     supplement thereto) in reliance upon and in conformity with information
     furnished in writing to the Partnership by or on behalf of any Underwriter
     through the Representatives specifically for inclusion in any of the
     Registration Statements or the Prospectus (or any supplement thereto).

         (c) The only significant subsidiaries (as defined in Regulation S-X
     under the Act) of the Partnership are the Intermediate Partnership,
     Northern Border Pipeline Company, a Texas general partnership ("Northern
     Border Pipeline"), Crestone Energy Ventures, L.L.C., a Delaware limited
     liability company ("Crestone"), Bear Paw Investments, LLC, a Delaware
     limited liability company ("Bear Paw Investments"), Bear Paw Energy, LLC, a
     Delaware limited liability company ("Bear Paw Energy"), Border Midwestern
     Company, a Delaware corporation ("Border Midwestern"), and Midwestern Gas
     Transmission Company, a Delaware corporation ("Midwestern Gas"). Each
     Subsidiary was duly formed and is validly existing and in good standing
     under the laws of its jurisdiction of formation. Each of the Subsidiaries
     has, and at the Closing Date will have, full power and authority to conduct
     the activities conducted by it, to own or lease all the assets owned or
     leased by it and to conduct its business as described in the Registration
     Statements and the Prospectus. Each of the Subsidiaries is, and at the
     Closing Date will be, duly licensed or qualified to do business and in good
     standing as a foreign entity in all jurisdictions in which the nature of
     the activities conducted by it or the character of the assets owned or
     leased by it makes such licensing or qualification necessary, except for
     such jurisdictions in which the failure so to qualify or register would not
     have a material adverse effect upon such Subsidiary or subject such
     Subsidiary or the Partnership to any material liability or disability. All
     of the outstanding interests of Crestone have been duly authorized and
     validly issued and are fully paid and non-assessable and are owned by the
     Intermediate Partnership free and clear of all liens, encumbrances and
     claims whatsoever. Crestone, directly or indirectly, owns (i) all of the
     membership interests in Crestone Gathering Services, L.L.C., Crestone Wind
     River, L.L.C. and Crestone Powder River, L.L.C. and (ii) a 49% common
     membership interest in and preferred shares of Bighorn Gas Gathering,
     L.L.C. ("Bighorn"), (iii) a 33.33% membership interest in Fort Union Gas
     Gathering, L.L.C., a Delaware limited liability company ("Fort Union"), and
     (iv) a 35% membership interest in Lost Creek Gathering, L.L.C., a Delaware
     limited liability company ("Lost Creek"), in each case free and clear of
     any liens, claims or encumbrances (except that Crestone's member interests
     in Fort Union and Lost Creek are or will be pledged to the lenders with
     respect to those projects and except for such other liens, encumbrances,
     security interests, equities, charges or claims as are not, individually or
     in the aggregate, material or except as described in the Prospectus). All
     of the outstanding


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     shares of capital stock of Border Midstream Services, Ltd., an Alberta
     corporation ("Border Midstream"), have been duly authorized and validly
     issued and are fully paid and non-assessable and are owned by the
     Intermediate Partnership free and clear of any liens, claims or
     encumbrances (except for such liens, encumbrances, security interests,
     equities, charges or claims as are not, individually or in the aggregate,
     material or except as described in the Prospectus). All of the outstanding
     interests of Bear Paw Investments have been duly authorized and validly
     issued and are fully paid and non-assessable and are owned by the
     Intermediate Partnership free and clear of any liens, claims or
     encumbrances (except for such liens, encumbrances, security interests,
     equities, charges or claims as are not, individually or in the aggregate,
     material or except as described in the Prospectus). All of the outstanding
     interests of Bear Paw Energy have been duly authorized and validly issued
     and are fully paid and non-assessable and are owned by Bear Paw Investments
     free and clear of any liens, claims or encumbrances (except for such liens,
     encumbrances, security interests, equities, charges or claims as are not,
     individually or in the aggregate, material or except as described in the
     Prospectus). All of the outstanding shares of capital stock of Border
     Midwestern have been duly authorized and validly issued and are fully paid
     and non-assessable and are owned by the Intermediate Partnership free and
     clear of any liens, claims or encumbrances (except for such liens,
     encumbrances, security interests, equities, charges or claims as are not,
     individually or in the aggregate, material or except as described in the
     Prospectus). All of the outstanding shares of capital stock of Midwestern
     Gas have been duly authorized and validly issued and are fully paid and
     non-assessable and are owned by Border Midwestern free and clear of any
     liens, claims or encumbrances (except for such liens, encumbrances,
     security interests, equities, charges or claims as are not, individually or
     in the aggregate, material or except as described in the Prospectus). The
     Intermediate Partnership owns a 70% general partner interest in Northern
     Border Pipeline free and clear of any liens, claims or encumbrances (except
     for such liens, encumbrances, security interests, equities, charges or
     claims as are not, individually or in the aggregate, material or except as
     described in the Prospectus).

         (d) The Partnership has been duly formed and is validly existing as a
     limited partnership under the Delaware Revised Uniform Limited Partnership
     Act (the "Delaware Act"), with all necessary partnership power and
     authority to own or lease the properties it owns or leases and to conduct
     the business it conducts in each case in all material respects as described
     in each of the Registration Statements and the Prospectus, and is duly
     qualified or registered as a foreign limited partnership for the
     transaction of business under the laws of each jurisdiction in which the
     failure so to qualify or register would have a material adverse effect upon
     the Partnership or subject the Partnership or the limited partners of the
     Partnership to any material liability or disability.

         (e) Northern Plains Natural Gas Company, a Delaware corporation
     ("Northern Plains") and wholly owned subsidiary of Enron Corp., an Oregon
     corporation ("Enron"), Pan Border Gas Company, a Delaware corporation ("Pan
     Border") and wholly owned subsidiary of Northern Plains, and Northwest
     Border Pipeline Company, a Delaware corporation ("Northwest Border") and
     wholly owned subsidiary of The Williams Companies, Inc., a Delaware
     corporation ("Williams") (collectively, the "General Partners"), are the
     only general partners of the Partnership with general partner interests


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     in the Partnership of 1.0% in the aggregate; such general partner interests
     are duly authorized by the Agreement of Limited Partnership of the
     Partnership (as it may be amended or restated at the Execution Date, the
     "Partnership Agreement"), and were validly issued to the General Partners
     and are fully paid (to the extent required under the Partnership
     Agreement).

         (f) The General Partners are the sole general partners of the
     Intermediate Partnership with general partner interests in the Intermediate
     Partnership of 1.0101% in the aggregate subject to the provisions of the
     Agreement of Limited Partnership of the Intermediate Partnership (the
     "Intermediate Partnership Agreement"); such general partner interests are
     duly authorized by the Intermediate Partnership Agreement and were validly
     issued to the General Partners and are fully paid (to the extent required
     under the Intermediate Partnership Agreement) (the Intermediate Partnership
     Agreement and the Partnership Agreement are herein collectively referred to
     as the "Partnership Agreements"). Complete and correct copies of the
     certificate of limited partnership for each of the Partnership and the
     Intermediate Partnership and of the Partnership Agreements, and all
     amendments thereto have been delivered to the Underwriters, and no changes
     therein will be made subsequent to the date hereof and prior to the Closing
     Date.

         (g) The limited partners of the Partnership hold limited partner
     interests in the Partnership aggregating 99.0%, such limited partner
     interests being represented by 37,623,014 Common Units, excluding
     Underwritten Securities sold by the Partnership hereunder; such limited
     partner interests are the only limited partner interests of the Partnership
     that are issued and outstanding; the limited partner interests represented
     thereby are authorized by the Partnership Agreement, were validly issued
     and are fully paid (to the extent required under the Partnership Agreement)
     and non-assessable (except as described in the Partnership Agreement and
     except as set forth in Section 17-607 of the Delaware Act).

         (h) The Partnership is the sole limited partner of the Intermediate
     Partnership, with a limited partner interest of 98.9899% (subject to the
     provisions of the Intermediate Partnership Agreement); such limited partner
     interest is authorized by the Intermediate Partnership Agreement, was
     validly issued in accordance with the Intermediate Partnership Agreement
     and is fully paid and non-assessable (except as described in the
     Intermediate Partnership Agreement and except as set forth in Section
     17-607 of the Delaware Act); the Partnership owns, directly or indirectly,
     such limited partner interest in the Intermediate Partnership free and
     clear of all liens, encumbrances, security interests, equities, charges or
     claims (except for such liens, encumbrances, security interests, equities,
     charges or claims as are not, individually or in the aggregate, material or
     except as described in any of the Registration Statements or Prospectus).

         (i) Except as described in the Prospectus or contained in the
     Partnership Agreement and except for (i) rights granted pursuant to that
     certain Exchange Agreement dated May 31, 1997 among the Intermediate
     Partnership, the Partnership and the stockholders of Williams Technologies,
     Inc. and (ii) rights granted pursuant to that certain Exchange Agreement
     dated December 29, 1997 between the Partnership and Central Pacific
     Resources Partnership, there are no preemptive rights or other rights to


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     subscribe for or to purchase, nor any restriction upon the voting or
     transfer of (except in the case of restrictions on transfer for securities
     issued by the Partnership in reliance on Section 4(2) of the Act), any
     limited partner interests in the Partnership or the Intermediate
     Partnership pursuant to either of the Partnership Agreements or other
     governing documents or any agreement or other instrument to which the
     Partnership or the Intermediate Partnership is a party or by which either
     of them may be bound. The Common Units conform in all material respects to
     the description of the Common Units contained in the Prospectus. Except as
     described above, there are no outstanding options or warrants to purchase
     any Common Units.

         (j) None of the Partnership or the Subsidiaries has sustained since the
     date of the latest audited financial statements incorporated by reference
     in each of the Registration Statements any material loss or interference
     with its business from fire, explosion, flood or other calamity, whether or
     not covered by insurance, or from any labor dispute or court or
     governmental action, order or decree, otherwise than as set forth or
     contemplated in the Prospectus; and, since the date as of which information
     is given in the Prospectus, there has not been any material adverse change
     in the capitalization or long-term debt of any of the Subsidiaries or any
     material adverse change, or any development involving a prospective
     material adverse change, in or affecting the general affairs, management,
     financial position, or results of operations of any of the Subsidiaries,
     otherwise than as set forth or contemplated in the Prospectus.

         (k) The Partnership and the Subsidiaries have good and indefeasible
     title to all real and personal property necessary to own and operate their
     businesses in all material respects as described in the Prospectus, free
     and clear of all liens, claims, encumbrances and defects except (1) as
     described in the Prospectus and (2) such as do not materially interfere
     with the ownership, operation or benefits of ownership of such businesses
     or materially increase the cost of operation or ownership of such
     businesses, provided that, (a) with respect to the gas transmission and
     gathering pipelines of Northern Border Pipeline, Crestone, Bear Paw Energy
     and Midwestern Gas and right-of-way interests related thereto (the
     "Pipeline Properties") the foregoing shall only constitute a representation
     that, except as described in the Prospectus, (i) Northern Border Pipeline,
     Crestone, Bear Paw Energy and Midwestern Gas have sufficient title to
     enable them to use such Pipeline Properties in their businesses as they
     have been used in the past and as are proposed to be used in the future as
     described in the Prospectus and (ii) any lack of title has not had and will
     not have any material adverse effect on the ability of Northern Border
     Pipeline, Crestone, Bear Paw Energy and Midwestern Gas to use such Pipeline
     Properties as they have been used in the past and are proposed to be used
     in the future as described in the Prospectus and will not materially
     increase the cost of such use, and (b) with respect to any real property,
     buildings and equipment held under lease by Northern Border Pipeline,
     Crestone, Bear Paw Energy or Midwestern Gas, such real property, buildings
     and equipment are held by Northern Border Pipeline, Crestone, Bear Paw
     Energy or Midwestern Gas under valid, subsisting and enforceable leases
     with such exceptions as are not material and do not interfere with the use
     made and proposed to be made of such real property, buildings and equipment
     by such person.


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         (l) The sale of the Securities by the Partnership and the compliance by
     the Partnership and the Intermediate Partnership with all of the provisions
     of this Agreement and the consummation of the transactions contemplated
     herein and in the Prospectus to be consummated at the Closing Date will not
     conflict with or result in a breach or violation of any of the terms or
     provisions of, or constitute a default under, any indenture, mortgage, deed
     of trust, loan agreement or other agreement or instrument to which the
     Partnership or any of the Subsidiaries is a party or by which any of them
     is bound or to which any of the property or assets of any of them is
     subject, nor will such action result in any violation of the provisions of
     the agreement of limited partnership, charter or other governing documents
     of the Partnership or any of the Subsidiaries or any statute or any order,
     rule or regulation of any court or governmental agency or body having
     jurisdiction over any of them or any of their properties; and no consent,
     approval, authorization, order, registration or qualification of or with
     any such court or governmental agency or body is required for the sale of
     the Securities or the consummation by the Partnership of the transactions
     contemplated herein and in the Prospectus to be consummated at the Closing
     Date, except for (i) such consents, approvals, authorizations,
     registrations or qualifications as may be required under state securities
     or Blue Sky laws in connection with the purchase and distribution of the
     Securities by the Underwriters, and (ii) such consents, approvals,
     authorizations, orders, registrations or qualifications (A) as have been
     obtained or will be obtained prior to the Closing Date or (B) that, if not
     obtained, would not, individually or in the aggregate, have a material
     adverse effect upon the holders of Common Units or the consolidated
     financial position or results of operations or prospects of the
     Partnership, the Intermediate Partnership or Northern Border Pipeline. The
     offering and sale of the Securities as contemplated by this Agreement does
     not give rise to any rights, other than those which have been waived or
     satisfied, for or relating to the registration of any Common Units or other
     securities of the Partnership or which would require the inclusion of any
     Common Units or other securities of the Partnership in such offering and
     sale of the Securities pursuant to "tag along" or other such rights.

         (m) Other than as set forth in the Prospectus, there are no legal or
     governmental proceedings pending to which the Partnership or any of the
     Subsidiaries is a party or of which any of their respective properties is
     the subject which, if determined adversely to such person, would
     individually or in the aggregate have a material adverse effect on the
     consolidated financial position or results of operations or prospects of
     the Partnership; and, to the best of the Partnership's knowledge, no such
     proceedings are threatened or contemplated by governmental authorities or
     threatened by others.

         (n) Arthur Andersen L.L.P., who have certified certain financial
     statements of Northern Border Pipeline, are independent public accountants
     with respect to Northern Border Pipeline, the Intermediate Partnership and
     the Partnership as required by the Act and the rules and regulations of the
     Commission thereunder;

         (o) (i) This Agreement has been duly authorized, executed and delivered
     by each of the Partnership and the Intermediate Partnership and constitutes
     the valid and binding agreement of each such person, (ii) the Partnership
     Agreement has been duly authorized, executed and delivered by the General
     Partners and is a valid and legally binding agreement of the General
     Partners, enforceable against the General Partners in


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     accordance with its terms, and (iii) the Intermediate Partnership Agreement
     has been duly authorized, executed and delivered by the parties thereto and
     is a valid and legally binding agreement of such parties, enforceable
     against the General Partners in accordance with its terms, except as the
     enforceability of the Partnership Agreements may be affected by (A) the
     matters described in the Prospectus and (B) bankruptcy, insolvency,
     reorganization and other laws of general applicability relating to or
     affecting creditors' rights and general equitable principles.

         (p) Each of the Partnership and the Subsidiaries carries, or is covered
     by, insurance in such amounts and covering such risks as is customarily
     obtained by businesses similarly situated, taking into account
     self-insurance.

         (q) None of the Partnership or the Subsidiaries is in, nor will
     consummation of the transactions contemplated herein or in the Prospectus
     to be consummated at the Closing Date result in: (i) violation of its
     charter, bylaws, agreement of limited or general partnership or other
     governing document (except for the failure to mail the reports identified
     in Section 8.3(b) of the Partnership Agreement); or (ii) default (and no
     event has occurred which, with notice or lapse of time or both, would
     constitute such a default) in the due performance or observance of any
     term, covenant or condition contained in any material contract, agreement,
     indenture or instrument to which it or its property may be subject, or
     violation of any law, ordinance, governmental rule, regulation or court
     decree to which it or its property may be subject, which default or
     violation, individually or in the aggregate, could have a material adverse
     effect on the holders of Common Units or the consolidated financial
     position or results of operations or prospects of any of the Partnership,
     the Intermediate Partnership or Northern Border Pipeline; and, except as
     described in the Prospectus, none of the Partnership or the Subsidiaries
     has failed to obtain any material license, permit, certificate, franchise
     or other governmental authorization or permit necessary to the ownership of
     its property or to the conduct of its business.

         (r) Neither the Partnership nor the Intermediate Partnership is, or at
     the Closing Date will be, (a) a "holding company" or "affiliate" of a
     holding company (other than an exempt holding company) or public utility,
     as defined in the Public Utility Holding Company Act of 1935 or (b) an
     "investment company" as that term is defined in the Investment Company Act
     of 1940, as amended (the "Investment Company Act"), and the rules and
     regulations thereunder;

         (s) Except as described in the Prospectus, the Partnership and the
     Subsidiaries possess, and are operating in compliance in all material
     respects with, all certificates, authorities or permits issued by the
     appropriate local, state, federal or foreign regulatory agencies or bodies
     necessary to conduct the business currently (or, as described or
     contemplated in the Prospectus, to be) operated by them, except for such
     certificates, authorizations or permits which, if not obtained, would not
     reasonably be expected to have, individually or in the aggregate, a
     material adverse effect upon the ability of the Partnership and the
     Subsidiaries to conduct their businesses in all material respects as
     currently conducted and as contemplated by the Prospectus to be conducted;
     and, except as described in the Prospectus, none of the Partnership or the
     Subsidiaries has received


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     any notice of proceedings relating to the revocation or modification of any
     such certificate, authorization or permit which, individually or in the
     aggregate, if the subject of an unfavorable decision, ruling or finding,
     would be expected to have a material adverse effect upon the ability of the
     Partnership or the Subsidiaries to conduct their businesses in all material
     respects as currently conducted and as contemplated by the Prospectus to be
     conducted.

         (t) Neither the Partnership nor the Intermediate Partnership has taken,
     directly or indirectly, any action designed to cause or result in, or which
     has constituted or which might reasonably be expected to constitute, the
     stabilization or manipulation of the price of the Common Units to
     facilitate the sale or resale of the Common Units in violation of any law,
     rule or regulation.

         (u) The financial statements of the Partnership (including the related
     notes and supporting schedules) filed as part of each of the Registration
     Statements or included in the Prospectus present fairly in all material
     respects the consolidated financial condition, results of operations and
     cash flows of the Partnership and its subsidiaries at the dates and for the
     periods indicated, and have been prepared in conformity with generally
     accepted accounting principles (except as otherwise described therein)
     applied on a consistent basis throughout the periods involved.

         (v) The Partnership maintains a system of internal accounting control
     sufficient to provide reasonable assurance that (i) transactions are
     executed in accordance with management's general or specific authorization;
     (ii) transactions are recorded as necessary to permit preparation of
     financial statements in conformity with generally accepted accounting
     principles and to maintain accountability for assets; (iii) access to
     assets is permitted only in accordance with management's general or
     specific authorization; and (iv) the recorded accountability for assets is
     compared with existing assets at reasonable intervals and appropriate
     action is taken with respect to any differences.

         (w) The Partnership and the Subsidiaries (i) are in compliance with any
     and all applicable foreign, federal, state and local laws and regulations
     relating to the protection of human health and safety, the environment or
     imposing liability or standards of conduct concerning any Hazardous
     Material (as hereinafter defined) ("Environmental Laws"), (ii) have
     received all permits, licenses or other approvals required of them under
     applicable Environmental Laws to conduct their respective businesses and
     (iii) are in compliance with all terms and conditions of any such permit,
     license or approval, except where such noncompliance with Environmental
     Laws, failure to receive required permits, licenses or other approvals or
     failure to comply with the terms and conditions of such permits, licenses
     or approvals would not, individually or in the aggregate, result in a
     material adverse effect on the condition (financial or otherwise) or on the
     earnings, business, properties, business prospects or operations of the
     Partnership and the Subsidiaries, taken as a whole. The term "Hazardous
     Material" means (A) any "hazardous substance" as defined by the
     Comprehensive Environmental Response, Compensation and Liability Act of
     1980, as amended, (B) any "hazardous waste" as defined by the Resource
     Conservation and Recovery Act, as amended, (C) any petroleum or petroleum
     product,


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     (D) any polychlorinated biphenyl and (E) any pollutant or contaminant or
     hazardous, dangerous, or toxic chemical, material, waste or substance
     regulated under or within the meaning of any other Environmental Law.

         (x) In the ordinary course of their businesses, the Partnership and the
     Subsidiaries conduct a periodic review of the effect of Environmental Laws
     on the business, operations and properties of the Partnership and the
     Subsidiaries, in the course of which they identify and evaluate associated
     costs and liabilities (including, without limitation, any capital or
     operating expenditures required for clean-up, closure of properties or
     compliance with Environmental Laws or any permit, license or approval, any
     related constraints on operating activities and any potential liabilities
     to third parties). Except as set forth in the Registration Statements and
     the Prospectus there are no costs and liabilities associated with or
     arising in connection with Environmental Laws as currently in effect
     (including, without limitation, costs of compliance therewith) which would,
     singly or in the aggregate have a material adverse effect on the condition
     (financial or otherwise) or on the earnings, business, properties, business
     prospects or operations of the Partnership and the Subsidiaries, taken as a
     whole.

         (y) The Partnership and the Subsidiaries are in compliance with all
     federal, state and local employment and labor laws, including, but not
     limited to, laws relating to non-discrimination in hiring, promotion and
     pay of employees; no labor dispute exists involving the employees of
     Northern Plains or NBP Services Corporation, a Delaware corporation, or, to
     the knowledge of the Partnership or the Intermediate Partnership, is
     imminent or threatened; and neither the Partnership nor the Intermediate
     Partnership is aware of any existing, imminent or threatened labor
     disturbance by the employees of any of its principal suppliers,
     manufacturers or contractors that could result in a material adverse effect
     on the condition (financial or otherwise) or on the earnings, business,
     properties, business prospects or operations of the Partnership and the
     Subsidiaries, taken as a whole.

         (z) The outstanding Common Units are listed for trading on the New York
     Stock Exchange, and the Underwritten Securities to be sold by the
     Partnership pursuant to this Agreement have been approved for listing on
     the New York Stock Exchange upon official notice of issuance.

         (ii) The Selling Unitholder represents and warrants to, and agrees
with, each Underwriter that:

         (a) The Selling Unitholder is the record and beneficial owner of the
     Securities to be sold by it hereunder free and clear of all liens,
     encumbrances, equities and claims and has duly endorsed such Securities in
     blank, and, assuming that each Underwriter acquires its interest in the
     Securities it has purchased from the Selling Unitholder without notice of
     any adverse claim (within the meaning of Section 8-105 of the New York
     Uniform Commercial Code ("UCC")), each Underwriter that has purchased such
     Securities delivered on the Closing Date to The Depository Trust Company or
     other securities intermediary by making payment therefor as provided
     herein, and that has had such Securities credited to the securities account
     or accounts of such Underwriters


                                       10
   11
     maintained with The Depository Trust Company or such other securities
     intermediary will have acquired a security entitlement (within the meaning
     of Section 8-102(a)(17) of the UCC) to such Securities purchased by such
     Underwriter, and no action based on an adverse claim (within the meaning of
     Section 8-105 of the UCC) may be asserted against such Underwriter with
     respect to such Securities.

         (b) The Selling Unitholder has not taken, directly or indirectly, any
     action designed to or that would constitute or that might reasonably be
     expected to cause or result in, under the Exchange Act or otherwise,
     stabilization or manipulation of the price of any security of the
     Partnership to facilitate the sale or resale of the Securities.

         (c) No consent, approval, authorization or order of any court or
     governmental agency or body is required for the consummation by the Selling
     Unitholder of the transactions contemplated herein, except such as may have
     been obtained under the Act and such as may be required under the blue sky
     laws of any jurisdiction in connection with the purchase and distribution
     of the Securities by the Underwriters and such other approvals as have been
     obtained.

         (d) Neither the sale of the Securities being sold by the Selling
     Unitholder nor the consummation of any other of the transactions herein
     contemplated by the Selling Unitholder or the fulfillment of the terms
     hereof by the Selling Unitholder will conflict with, result in a breach or
     violation of, or constitute a default under (i) the charter or by-laws of
     the Selling Unitholder or (ii) any law or the terms of any indenture or
     other agreement or instrument to which the Selling Unitholder or any of its
     affiliates is a party or bound, or any judgment, order or decree applicable
     to the Selling Unitholder or any of its affiliates of any court, regulatory
     body, administrative agency, governmental body or arbitrator having
     jurisdiction over the Selling Unitholder or any of its affiliates, except
     in the case of clause (ii) as would not have a material adverse effect on
     the Selling Unitholder's performance of its obligations hereunder.

         (e) The sale of Securities by the Selling Unitholder pursuant hereto is
     not prompted by any information concerning the Partnership or any of the
     Subsidiaries which is not set forth in the Prospectus or any supplement
     thereto.

         (f) The information in the Prospectus under the caption "Principal and
     Selling Unitholders" which specifically relates to the Selling Unitholder
     does not, and will not on the Closing Date, contain any untrue statement of
     a material fact or omit to state any material fact required to be stated
     therein or necessary to make the statements therein, in the light of the
     circumstances in which they were made, not misleading.


         Any certificate signed by any officer of the Selling Unitholder and
delivered to the Representatives or counsel for the Underwriters in connection
with the offering of the Securities shall be deemed a representation and
warranty by the Selling Unitholder, as to matters covered thereby, to each
Underwriter.


                                       11
   12
         2. Purchase and Sale. (a) Subject to the terms and conditions and in
reliance upon the representations and warranties herein set forth, the
Partnership and the Selling Unitholder agree, severally and not jointly, to sell
to each Underwriter, and each Underwriter agrees, severally and not jointly, to
purchase from the Partnership and the Selling Unitholder, at a purchase price of
$39.56 per Common Unit, the amount of the Underwritten Securities set forth
opposite such Underwriter's name in Schedule I hereto.

         (b) Subject to the terms and conditions and in reliance upon the
     representations and warranties herein set forth, the Selling Unitholder
     named in Schedule II hereto hereby grants an option to the several
     Underwriters to purchase, severally and not jointly, up to 668,282 Option
     Securities at the same purchase price per share as the Underwriters shall
     pay for the Underwritten Securities. Said option may be exercised only to
     cover over-allotments in the sale of the Underwritten Securities by the
     Underwriters. Said option may be exercised in whole or in part at any time
     (but not more than once) on or before the 30th day after the date of the
     Prospectus upon written or telegraphic notice by the Representatives to the
     Partnership and the Selling Unitholder setting forth the number of units of
     the Option Securities as to which the several Underwriters are exercising
     the option and the settlement date. The number of Option Securities to be
     purchased by each Underwriter shall be the same percentage of the total
     number of units of the Option Securities to be purchased by the several
     Underwriters as such Underwriter is purchasing of the Underwritten
     Securities, subject to such adjustments as you in your absolute discretion
     shall make to eliminate any fractional units.

         3. Delivery and Payment. Delivery of and payment for the Underwritten
Securities and the Option Securities (if the option provided for in Section 2(b)
hereof shall have been exercised on or before the third Business Day prior to
the Closing Date) shall be made at 10:00 AM, New York City time, on May 22,
2001, or at such time on such later date not more than three Business Days after
the foregoing date as the Representatives shall designate, which date and time
may be postponed by agreement among the Representatives, the Partnership and the
Selling Unitholder or as provided in Section 9 hereof (such date and time of
delivery and payment for the Securities being herein called the "Closing Date").
Delivery of the Securities shall be made to the Representatives for the
respective accounts of the several Underwriters against payment by the several
Underwriters through the Representatives of the respective aggregate purchase
prices of the Securities being sold by the Partnership and the Selling
Unitholder to or upon the order of the Partnership and the Selling Unitholder by
wire transfer payable in same-day funds to the accounts specified by the
Partnership and the Selling Unitholder. Delivery of the Underwritten Securities
and the Option Securities shall be made through the facilities of The Depository
Trust Company unless the Representatives shall otherwise instruct.

         The Selling Unitholder will pay all applicable state transfer taxes, if
any, involved in the transfer to the several Underwriters of the Securities to
be purchased by them from such Selling Unitholder and the respective
Underwriters will pay any additional transfer taxes involved in further
transfers.

         If the option provided for in Section 2(b) hereof is exercised after
the third Business Day prior to the Closing Date, the Selling Unitholder named
in Schedule II hereto will


                                       12
   13
deliver the Option Securities (at the expense of the Partnership) to the
Representatives, at 388 Greenwich Street, New York, New York, on the date
specified by the Representatives (which shall be within three Business Days
after exercise of said option) for the respective accounts of the several
Underwriters, against payment by the several Underwriters through the
Representatives of the purchase price thereof to or upon the order of the
Selling Unitholder named in Schedule II by wire transfer payable in same-day
funds to the account(s) specified by the Selling Unitholder named in Schedule II
hereto. If settlement for the Option Securities occurs after the Closing Date,
the Partnership and the Selling Unitholder will deliver to the Representatives
on the settlement date for the Option Securities, and the obligation of the
Underwriters to purchase the Option Securities shall be conditioned upon receipt
of, supplemental opinions, certificates and letters confirming as of such date
the opinions, certificates and letters delivered on the Closing Date pursuant to
Section 6 hereof.

         4. Offering by Underwriters. It is understood that the several
Underwriters propose to offer the Securities for sale to the public as set forth
in the Prospectus.

         5. Agreements.

         (i) The Partnership and the Intermediate Partnership agree with the
several Underwriters that:

         (a) Prior to the termination of the offering of the Securities, the
     Partnership will not file any amendment of any of the Registration
     Statements, any supplement to the Prospectus or any Rule 462(b)
     Registration Statement unless the Partnership has furnished you a copy for
     your review prior to filing and will not file any such proposed amendment
     or supplement to which you reasonably object. Subject to the foregoing
     sentence, if any of the Registration Statements have become or become
     effective pursuant to Rule 430A, or filing of the Prospectus is otherwise
     required under Rule 424(b), the Partnership will cause the Prospectus,
     properly completed, and any supplement thereto to be filed with the
     Commission pursuant to the applicable paragraph of Rule 424(b) within the
     time period prescribed and will provide evidence satisfactory to the
     Representatives of such timely filing. The Partnership will promptly advise
     the Representatives (1) when each of the Registration Statements, if not
     effective at the Execution Time, shall have become effective, (2) when the
     Prospectus, and any supplement thereto, shall have been filed (if required)
     with the Commission pursuant to Rule 424(b) or when any Rule 462(b)
     Registration Statement shall have been filed with the Commission, (3) when,
     prior to termination of the offering of the Securities, any amendment of
     any of the Registration Statements shall have been filed or become
     effective, (4) of any request by the Commission or its staff for any
     amendment of any of the Registration Statements, or any Rule 462(b)
     Registration Statement, or for any supplement to the Prospectus or for any
     additional information, (5) of the issuance by the Commission of any stop
     order suspending the effectiveness of any of the Registration Statements or
     the institution or threatening of any proceeding for that purpose and (6)
     of the receipt by the Partnership of any notification with respect to the
     suspension of the qualification of the Securities for sale in any
     jurisdiction or the institution or threatening of any proceeding for such
     purpose. The Partnership and the Intermediate Partnership will use their
     best efforts to


                                       13
   14
     prevent the issuance of any such stop order or the suspension of any such
     qualification and, if issued, to obtain as soon as possible the withdrawal
     thereof.

         (b) If, at any time when a prospectus relating to the Securities is
     required to be delivered under the Act, any event occurs as a result of
     which the Prospectus as then supplemented would include any untrue
     statement of a material fact or omit to state any material fact necessary
     to make the statements therein in the light of the circumstances under
     which they were made not misleading, or if it shall be necessary to amend
     any of the Registration Statements or supplement the Prospectus to comply
     with the Act or the Exchange Act, the Partnership promptly will (1) notify
     the Representatives of such event, (2) prepare and file with the
     Commission, subject to the second sentence of paragraph (i)(a) of this
     Section 5, an amendment or supplement which will correct such statement or
     omission or effect such compliance and (3) supply any supplemented
     Prospectus to you in such quantities as you may reasonably request.

         (c) As soon as practicable, the Partnership will make generally
     available to its security holders and to the Representatives an earnings
     statement or statements of the Partnership and its subsidiaries which will
     satisfy the provisions of Section 11(a) of the Act and Rule 158 under the
     Act.

         (d) The Partnership will furnish to the Representatives and counsel for
     the Underwriters, without charge, one signed copy of each of the
     Registration Statements (including exhibits thereto) and to each other
     Underwriter copies of each of the Registration Statements (without exhibits
     thereto) and, so long as delivery of a prospectus by an Underwriter or
     dealer may be required by the Act, as many copies of each Preliminary
     Prospectus and the Prospectus and any supplement thereto as the
     Representatives may reasonably request. The Partnership will pay the
     expenses of printing or other production of all documents relating to the
     offering.

         (e) The Partnership will arrange, if necessary, for the qualification
     of the Securities for sale under the laws of such jurisdictions as the
     Representatives may designate, will maintain such qualifications in effect
     so long as required for the distribution of the Securities and will pay any
     fee of the National Association of Securities Dealers, Inc., in connection
     with its review of the offering; provided that in no event shall the
     Partnership be obligated to qualify to do business in any jurisdiction
     where it is not now so qualified or to take any action that would subject
     it to service of process in suits, other than those arising out of the
     offering or sale of the Securities, in any jurisdiction where it is not now
     so subject.

         (f) The Partnership will not, without the prior written consent of
     Salomon Smith Barney Inc., offer, sell, contract to sell, pledge, or
     otherwise dispose of, (or enter into any transaction which is designed to,
     or might reasonably be expected to, result in the disposition (whether by
     actual disposition or effective economic disposition due to cash settlement
     or otherwise) by the Partnership or any affiliate of the Partnership or any
     person in privity with the Partnership or any affiliate of the Partnership)
     directly or indirectly, including the filing (or participation in the
     filing) of a registration statement with the Commission in respect of
     (except for the filing of a shelf registration statement


                                       14
   15
     (the "Bear Paw Shelf Registration Statement") filed with the Commission
     pursuant to Section 11.7 of the Acquisition Agreement, dated March 14, 2001
     (the "Acquisition Agreement"), among the Partnership, the Intermediate
     Partnership, Bear Paw Investments, Bear Paw Energy and the other parties
     named therein), or establish or increase a put equivalent position or
     liquidate or decrease a call equivalent position within the meaning of
     Section 16 of the Exchange Act, any other Common Units or any securities
     convertible into, or exercisable, or exchangeable for, Common Units; or
     publicly announce an intention to effect any such transaction (other than
     by filing the Bear Paw Shelf Registration Statement as described above),
     for a period of ninety (90) days after the date of this Agreement,
     provided, however, that the Partnership may issue and sell Common Units
     pursuant to any employee unit option plan, unit ownership plan or dividend
     reinvestment plan of the Partnership in effect at the Execution Time and
     the Partnership may issue Common Units issuable upon the conversion of
     securities or the exercise of warrants outstanding at the Execution Time.

         (g) The Partnership will not take, directly or indirectly, any action
     designed to or that would constitute or that might reasonably be expected
     to cause or result in, under the Exchange Act or otherwise, stabilization
     or manipulation of the price of any security of the Partnership to
     facilitate the sale or resale of the Securities.

         (ii) The Selling Unitholder agrees with the several Underwriters that:

         (a) Except pursuant to this Agreement, the Selling Unitholder will not,
     without the prior written consent of Salomon Smith Barney Inc., offer,
     sell, contract to sell, pledge or otherwise dispose of (or enter into any
     transaction which is designed to, or might reasonably be expected to,
     result in the disposition (whether by actual disposition or effective
     economic disposition due to cash settlement or otherwise) by the Selling
     Unitholder or any affiliate of the Selling Unitholder or any person in
     privity with the Selling Unitholder or any affiliate of the Selling
     Unitholder) directly or indirectly, or file (or participate in the filing
     of) a registration statement with the Commission in respect of, or
     establish or increase a put equivalent position or liquidate or decrease a
     call equivalent position within the meaning of Section 16 of the Exchange
     Act with respect to, any Common Units of the Partnership or any securities
     convertible into or exercisable or exchangeable for such Common Units, or
     publicly announce an intention to effect any such transaction, for a period
     of ninety (90) days after the date of this Agreement, other than Common
     Units disposed of as bona fide gifts approved by Salomon Smith Barney Inc.

         (b) The Selling Unitholder will not take, directly or indirectly, any
     action designed to or that would constitute or that might reasonably be
     expected to cause or result in, under the Exchange Act or otherwise,
     stabilization or manipulation of the price of any security of the
     Partnership to facilitate the sale or resale of the Securities.

         (c) The Selling Unitholder will advise you promptly, and if requested
     by you, will confirm such advice in writing, so long as delivery of a
     prospectus relating to the Securities by an underwriter or dealer may be
     required under the Act, of (i) any material change in the Partnership's
     condition (financial or otherwise), prospects, earnings,


                                       15
   16
     business or properties which comes to the attention of the Selling
     Unitholder, (ii) any change in information in any of the Registration
     Statements or the Prospectus relating to the Selling Unitholder or (iii)
     any new material information relating to the Partnership or relating to any
     matter stated in the Prospectus which comes to the attention of the Selling
     Unitholder.

         6. Conditions to the Obligations of the Underwriters. The obligations
of the Underwriters to purchase the Underwritten Securities and the Option
Securities, as the case may be, shall be subject to the accuracy of the
representations and warranties on the part of the Partnership and the Selling
Unitholder contained herein as of the Execution Time, the Closing Date and any
settlement date pursuant to Section 3 hereof, to the accuracy of the statements
of the Partnership and the Selling Unitholder made in any certificates pursuant
to the provisions hereof, to the performance by the Partnership and the Selling
Unitholder of their respective obligations hereunder and to the following
additional conditions:

         (a) If filing of the Prospectus, or any supplement thereto, is required
     pursuant to Rule 424(b), the Prospectus, and any such supplement, will be
     filed in the manner and within the time period required by Rule 424(b); and
     no stop order suspending the effectiveness of any of the Registration
     Statements shall have been issued and no proceedings for that purpose shall
     have been instituted or threatened.

         (b) The Partnership shall have requested and caused Vinson & Elkins
     L.L.P., counsel for the Partnership, to have furnished to the
     Representatives their opinion, dated the Closing Date and addressed to the
     Representatives, to the effect that:

               (i) Each of the Partnership and the Intermediate Partnership has
         been duly formed and is validly existing as a limited partnership under
         the Delaware Act, with full partnership power and authority under the
         Delaware Act and the Partnership Agreement and the Intermediate
         Partnership Agreement, respectively, necessary to own, lease and
         operate its properties and conduct its business as described in the
         Prospectus;

               (ii) The Partnership has been registered as a foreign limited
         partnership for the transaction of business under the laws of the State
         of Texas, and to our knowledge based upon a certificate (a copy of
         which has been furnished to you and your counsel) from an authorized
         officer of the Partnership as to the states in which the Partnership
         owns or leases property or conducts business, the State of Texas is the
         only jurisdiction in which the Partnership owns or leases property or
         conducts business so as to require qualification or registration to
         conduct business as a foreign limited partnership, except where the
         failure to so qualify or register would not (i) have a material adverse
         effect upon the Partnership, the Intermediate Partnership or the
         General Partners or (ii) subject the limited partners of the
         Partnership to any material liability or disability;

               (iii) The Intermediate Partnership has been qualified or
         registered as a foreign limited partnership for the transaction of
         business under the laws of the States of Illinois, Iowa, Minnesota,
         Montana, Nebraska, North Dakota, South


                                       16
   17
         Dakota and Texas, and to our knowledge based upon a certificate (a copy
         of which has been furnished to you and your counsel) from an authorized
         officer of the Partnership as to the states in which the Partnership
         owns or leases property or conducts business, such jurisdictions are
         the only jurisdictions in which the Intermediate Partnership owns or
         leases property or conducts business so as to require qualification or
         registration to conduct business as a foreign limited partnership,
         except where the failure to so qualify or register would not (i) have a
         material adverse effect upon the Partnership, the Intermediate
         Partnership or the General Partners or (ii) subject the limited
         partners of the Partnership to any material liability or disability;

               (iv) The General Partners are the sole general partners of each
         of the Partnership and the Intermediate Partnership with a combined
         general partner interest in the Partnership of 1.0% and a combined
         general partner interest in the Intermediate Partnership of 1.0101%
         (subject to the provisions of the Partnership Agreement and the
         Intermediate Partnership Agreement, respectively); such general partner
         interests are duly authorized by the Partnership Agreement and the
         Intermediate Partnership Agreement, respectively, are validly issued
         and fully paid (to the extent required by the Partnership Agreement and
         Intermediate Partnership Agreement) and are owned of record by the
         General Partners free and clear of all liens, encumbrances, security
         interests, equities, charges or claims of record (except as provided in
         the Partnership Agreement, the Intermediate Partnership Agreement or
         the Northern Border Pipeline Partnership Agreement or pursuant to the
         Delaware Act, as amended) (A) in respect of which a financing statement
         under the Uniform Commercial Code of the State of Delaware naming a
         General Partner as debtor is on file in the offices of the Secretary of
         State of the State of Delaware or (B) otherwise known to us;

               (v) The Partnership is the sole limited partner of the
         Intermediate Partnership, with a limited partner interest in the
         Intermediate Partnership of 98.9899% (subject to the provisions of the
         Intermediate Partnership Agreement); such limited partner interest is
         duly authorized by the Intermediate Partnership Agreement and is
         validly issued, fully paid and non-assessable, except as provided in
         Section 17-607 of the Delaware Act; and the Partnership owns such
         limited partner interest in the Intermediate Partnership free and clear
         of all liens, encumbrances, security interests, equities, charges or
         claims of record (except as provided in the Intermediate Partnership
         Agreement or pursuant to the Delaware Revised Uniform Limited
         Partnership Act, as amended) (A) in respect of which a financing
         statement under the Uniform Commercial Code of the State of Delaware
         naming the Partnership as debtor is on file in the offices of the
         Secretary of State of the State of Delaware or (B) otherwise known to
         us;

               (vi) Immediately prior to the closing under this Agreement, the
         limited partners of the Partnership held limited partner interests in
         the Partnership aggregating 99.0% (subject to the provisions of the
         Partnership Agreement); such limited partner interests are represented
         by 37,623,014 Common Units; such limited partner interests and the
         Underwritten Securities sold by the Partnership


                                       17
   18
         will be the only limited partner interests of the Partnership that are
         issued and outstanding immediately following the closing under this
         Agreement; the Underwritten Securities sold by the Partnership are
         authorized by the Partnership Agreement and are validly issued, fully
         paid and non-assessable, except as provided in Section 17-607 of the
         Delaware Act;

               (vii) Insofar as such descriptions relate to legal matters or
         descriptions of provisions of the governing instruments, the Common
         Units conform in all material respects to the descriptions thereof
         contained in the Prospectus;

               (viii) Except as described in the Prospectus and contained in the
         Partnership Agreement and except for (i) rights granted pursuant to
         that certain Exchange Agreement dated May 31, 1997 among the
         Intermediate Partnership, the Partnership and the stockholders of
         Williams Technologies, Inc. and (ii) rights granted pursuant to that
         certain Exchange Agreement dated December 29, 1997 between the
         Partnership and Central Pacific Resources Partnership, there are no
         preemptive or other rights to subscribe for or to purchase any limited
         partner interests of the Partnership or the Intermediate Partnership
         pursuant to the Partnership Agreements or, to our knowledge, pursuant
         to any other agreement or instrument to which the Partnership or the
         Intermediate Partnership is a party; and except as described in the
         Prospectus and except for restrictions on transfer of securities issued
         by the Partnership in reliance on Section 4(2) of the Act, there are no
         restrictions upon the voting or transfer of any limited partner
         interests of the Partnership or the Intermediate Partnership pursuant
         to the Partnership Agreements or, to our knowledge, pursuant to any
         other agreement or instrument to which the Partnership or the
         Intermediate Partnership is a party.

               (ix) The Registration Statements were declared effective under
         the Act on December 5, 1997, March 3, 1999 and March 3, 1999,
         respectively; the Prospectus was filed with the Commission pursuant to
         subparagraph (5) of Rule 424(b) on May 17, 2001; and no stop order
         suspending the effectiveness of any of the Registration Statements has
         been issued and, to our knowledge, no proceeding for that purpose is
         pending or threatened by the Commission;

               (x) Each of the Registration Statements and the Prospectus and
         any further amendments or supplements thereto made by the Partnership
         prior to the Closing Date (other than the financial statements and
         related schedules or other financial or statistical data and the
         projected data included therein, as to which we express no opinion)
         comply as to form in all material respects with the requirements of the
         Act;

               (xi) To our knowledge, there are no contracts or other documents
         that are required to be summarized or described in the Prospectus or
         filed as exhibits to any of the Registration Statements by the Act that
         have not been summarized, described or incorporated by reference in the
         Prospectus or filed as exhibits to such Registration Statement(s);


                                       18
   19
               (xii) The statements contained in the Prospectus under the
         captions "Tax Considerations" and "Recent Tax Developments," insofar as
         they describe federal statutes, rules and regulations, constitute a
         fair summary thereof that is accurate in all material respects; our
         opinions filed as Exhibit 8 to each of the Registration Statements and
         as Exhibit 8 to the Partnership's Form 8-K filed on May 17, 2001, are
         confirmed, and you may rely upon such opinions as if each of them were
         addressed to you;

               (xiii) This Agreement has been duly authorized, executed and
         delivered by each of the Partnership and the Intermediate Partnership;
         assuming due authorization, execution and delivery by, and the
         validity, legally binding effect and enforceability with respect to,
         the other parties thereto, the General Partnership Agreement governing
         Northern Border Pipeline, as amended and in effect on the date hereof,
         and each of the Partnership Agreements constitute valid and legally
         binding agreements of each of the Partnership, the Intermediate
         Partnership and the General Partners (in each case, to the extent a
         party thereto) and are enforceable against each such party in
         accordance with their respective terms, subject to the qualifications
         that (A) the enforceability of each such agreement may be limited by
         bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium
         and other similar laws of general applicability relating to or
         affecting the rights of creditors generally, (B) the enforceability of
         each such agreement may be limited by public policy, applicable law
         relating to fiduciary duties and the judicial imposition of an implied
         covenant of good faith and fair dealing, (C) the enforceability of
         equitable rights and remedies provided for in each such agreement is
         subject to equitable defenses and judicial discretion, and (D) the
         enforceability of certain other provisions of each such agreement may
         be limited by applicable laws and court decisions, none of which should
         materially and adversely interfere with the practical realization of
         the material benefits intended to be provided by such agreements;

               (xiv) The compliance by each of the Partnership and the
         Intermediate Partnership with all of the provisions of this Agreement
         will not, with the passage of time or upon stated contingency or
         otherwise, (A) conflict with or result in a breach or violation of any
         of the terms or provisions of, or constitute a default under, any of
         the agreements filed or incorporated by reference as exhibits to the
         Partnership's Annual Report on Form 10-K for the year ended December
         31, 2000 (the "2000 10-K") or any report filed by the Partnership with
         the Commission subsequent to the filing of the 2000 10-K, or (B) result
         in any breach or violation of the provisions of the certificate of
         limited partnership of the Partnership or the Intermediate Partnership
         or of any statute or any rule or regulation of any governmental agency
         or body having jurisdiction over either of such entities or its
         properties, excluding in each case any breaches or violations which,
         individually or in the aggregate, would not have a material adverse
         effect on the limited partners of the Partnership or the financial
         condition, results of operation, business or prospects (as described in
         the Prospectus) of the Partnership and the Intermediate Partnership
         considered as a whole;


                                       19
   20
               (xv) Except as described in the Prospectus, or as provided in the
         Partnership Agreement and the Acquisition Agreement, to our knowledge
         there are no contracts, agreements or understandings between the
         Partnership, the Intermediate Partnership or the General Partners and
         any person granting such person the right to require the Partnership to
         file a registration statement under the Act with respect to any
         securities of the Partnership owned or to be owned by such person or to
         require the Partnership to include such securities in the securities
         registered pursuant to any of the Registration Statements or in any
         securities being registered pursuant to any other registration
         statement filed by the Partnership under the Act; and none of such
         rights described in this paragraph would require any such securities to
         be included in the offering and sale of the Securities;

               (xvi) Neither the Partnership nor the Intermediate Partnership is
         an "investment company" as that term is defined in the Investment
         Company Act and the rules and regulations thereunder and each General
         Partner is either (A) not an "investment company" as that term is
         defined in the Investment Company Act and the rules and regulations
         thereunder or (B) exempt from the Investment Company Act;

               (xvii) None of the Partnership, the Intermediate Partnership or
         any General Partner is a "public utility company," a "holding company"
         or an "affiliate" of a holding company (other than an exempt holding
         company) or a public utility company within the meaning of the Public
         Utility Holding Company Act of 1935, as amended;

               (xviii) No consent, approval, authorization, order, registration
         or qualification of or with any federal governmental agency or body or
         any governmental agency or body of the State of Texas is required for
         the sale of the Common Units or the consummation by any of the
         Partnership, the Intermediate Partnership, the General Partners of the
         transactions contemplated by this Agreement and the Prospectus, except
         (i) such consents, approvals, authorizations, orders, registrations or
         qualifications (a) as have been obtained, (b) as may be required under
         state securities or Blue Sky laws, or (c) which, if not obtained, would
         not, individually or in the aggregate, have a material adverse effect
         upon the ability of the Partnership and the Intermediate Partnership to
         conduct their business as described in the Prospectus;

               (xix) The Common Units outstanding immediately prior to the
         closing under this Agreement are listed on the New York Stock Exchange,
         and the Underwritten Securities issued by the Partnership pursuant to
         this Agreement have been approved for listing on the New York Stock
         Exchange, subject to notice of issuance; and

               (xx) Northern Border Pipeline is validly existing as a general
         partnership under the laws of the State of Texas, with full partnership
         power and authority to


                                       20
   21
         own, lease and operate its properties and conduct its business in all
         material respects as described in the Prospectus.

               (xxi) Assuming that each Underwriter acquires its interest in the
         Securities it has purchased from the Selling Unitholder without notice
         of any adverse claim (within the meaning of Section 8-105 of the UCC),
         each Underwriter that has purchased such Securities delivered on the
         Closing Date to The Depository Trust Company or other securities
         intermediary by making payment therefor as provided herein, and that
         has had such Securities credited to the securities account or accounts
         of such Underwriters maintained with The Depository Trust Company or
         such other securities intermediary will have acquired a security
         entitlement (within the meaning of Section 8-102(a)(17) of the UCC) to
         such Securities purchased by such Underwriter, and no action based on
         an adverse claim (within the meaning of Section 8-105 of the UCC) may
         be asserted against such Underwriter with respect to such Securities.

         In addition, such counsel shall state that in the course of preparation
     by the Partnership of the Registration Statements, the Preliminary
     Prospectus and the Prospectus, such counsel participated in conferences
     with officers and other representatives of the Partnership and certain of
     the Subsidiaries, representatives of the independent public accountants of
     the Partnership and, in the case of the Preliminary Prospectus and the
     Prospectus, your representatives, at which the contents of the Registration
     Statements, the Preliminary Prospectus and Prospectus and related matters
     were discussed. Such counsel shall also state that although they have not
     conducted any independent investigation with regard to the information set
     forth in the Registration Statements or the Prospectus (except with respect
     to the foregoing opinions) and are not (except as aforesaid) passing upon
     and do not assume any responsibility for the accuracy, completeness or
     fairness of the statements contained therein, on the basis of the
     foregoing, no facts have come to such counsel's attention that cause such
     counsel to believe that any of the Registration Statements or any amendment
     thereto on its respective Effective Date, or as supplemented or amended at
     the Closing Date, contained any untrue statement of a material fact or
     omitted to state a material fact required to be stated therein or necessary
     to make the statements therein not misleading, or that, as of its date or
     the Closing Date, the Prospectus or any further amendment or supplement
     thereto contained an untrue statement of a material fact or omitted a
     material fact required to be stated therein or necessary to make the
     statements therein, in light of the circumstances under which they were
     made, not misleading. In making such statement, such counsel may state that
     they do not express any comment with respect to the financial statements
     and related schedules and other financial data included or incorporated by
     reference in the Registration Statements or in the Prospectus or any
     further amendment or supplement thereto (including, without limitation,
     statements relating to projected cash distributions to the limited partners
     of the Partnership) or any statement contained therein or omitted therefrom
     in reliance upon and in conformity with written information furnished to
     the Partnership by any Underwriter through you expressly for use therein.

         In rendering such opinion, such counsel may rely (A) as to matters
     involving the application of the Delaware Act, the Delaware Limited
     Liability Company Act, the

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     Delaware General Corporation Law and the laws of the States of New York and
     Texas, to the extent they deem proper and specified in such opinion, upon
     the opinion of other counsel of good standing whom they believe to be
     reliable and who are satisfactory to counsel for the Underwriters and (B)
     as to matters of fact, to the extent they deem proper, on certificates of
     responsible officers of the Partnership and public officials. References to
     the Prospectus in this paragraph (b) include any supplements thereto at the
     Closing Date.

         (c) The Partnership shall have requested and caused Janet K. Place,
     Esq., General Counsel of Northern Plains, to have furnished to the
     Representatives her opinion with respect to the Common Units, dated the
     Closing Date and addressed to the Representatives, to the effect that:

               (i) Other than as set forth in the Prospectus, to her knowledge
         there are no legal or governmental proceedings pending to which the
         Partnership or any of the Subsidiaries is a party or of which any
         property of any of them is the subject which, if determined adversely
         to such person, would individually or in the aggregate have a material
         adverse effect on the Partnership and its Subsidiaries taken as a whole
         (a "Material Adverse Effect"); and, to her knowledge, no such
         proceedings are threatened or contemplated by governmental authorities
         or threatened by others.

               (ii) Except as described in the Prospectus, to her knowledge each
         of the Partnership and the Subsidiaries possesses, and is operating in
         compliance in all material respects with, all certificates, authorities
         or permits issued by the appropriate local, state or federal regulatory
         agencies or bodies necessary to conduct its business as it is currently
         conducted as described in the Prospectus, except for such certificates,
         authorizations or permits which, if not obtained, would not reasonably
         be expected to have, individually or in the aggregate, a material
         adverse effect upon the ability of the Partnership and each of the
         Subsidiaries to conduct its businesses in all material respects as
         currently conducted as described in the Prospectus; to her knowledge,
         the Partnership and each of the Subsidiaries possesses all
         certificates, authorities or permits issued by the appropriate local,
         state or federal regulatory agencies or bodies necessary to conduct its
         business as proposed to be conducted as described in the Prospectus,
         except for (a) certificates, authorizations or permits that, if not
         obtained, would not reasonably be expected to have, individually or in
         the aggregate, a Material Adverse Effect; and (b) certificates,
         authorizations or permits that are reasonably expected to be obtained
         in the ordinary course of business; and, except as described in the
         Prospectus, none of the Partnership or any of the Subsidiaries has
         received any notice of proceedings relating to the revocation or
         modification of any such certificate, authorization or permit which,
         individually or in the aggregate, if the subject of an unfavorable
         decision, ruling or finding, would be expected to have a Material
         Adverse Effect. All government regulations, authorizations and
         procedures which affect the Partnership or any of the Subsidiaries and
         the operation of their respective businesses and that are required to
         be described in the Prospectus are as described therein.


                                       22
   23
               (iii) The Partnership and each of the Subsidiaries (1) is in
         compliance with any and all applicable Environmental Laws, (2) has
         received all permits, licenses or other approvals required of them
         under applicable Environmental Laws to conduct its business and (3) is
         in compliance with all terms and conditions of any such permit, license
         or approval, except where such noncompliance with Environmental Laws,
         failure to receive required permits, licenses or other approvals or
         failure to comply with the terms and conditions of such permits,
         licenses or approvals would not, individually or in the aggregate,
         result in a Material Adverse Effect; provided, such counsel may qualify
         such opinions to her knowledge with respect to Bear Paw Investments,
         Bear Paw Energy, Border Midwestern and Midwestern Gas.

               (iv) None of the Partnership or any of the Subsidiaries is: (i)
         in violation of its charter, bylaws, agreement of limited or general
         partnership or other governing document (except for the failure to mail
         the reports identified in Section 8.3(b) of the Partnership Agreement),
         (ii) in default in any material respect, and no event has occurred
         which, with notice or lapse of time or both, would constitute such a
         default, in the due performance or observance of any term, covenant or
         condition contained in any indenture, mortgage, deed of trust, loan
         agreement or other agreement or instrument to which it is a party or by
         which it is bound or to which any of its properties or assets is
         subject, or (iii) other than as set forth in the Prospectus, in
         violation in any material respect of any law, ordinance, government
         rule, regulation or court decree to which it or its properties or
         assets may be subject, except for such violations and defaults that
         would not, individually or in the aggregate, result in an Material
         Adverse Effect; provided, such counsel may qualify the opinion in this
         clause (iii) to her knowledge with respect to Bear Paw Investments,
         Bear Paw Energy, Border Midwestern and Midwestern Gas.

               (v) Since the date as of which information is given in the
         Prospectus through the date hereof, and except as may otherwise be
         disclosed in the Prospectus, the Partnership has not (i) issued or
         granted any partner interests, (ii) incurred any material liability or
         obligation, direct or contingent, other than liabilities and
         obligations that were incurred in the ordinary course of business,
         (iii) entered into any material transaction not in the ordinary course
         of business or (iv) distributed any of the cash or other assets of the
         Partnership to any partner.

               (vi) The Partnership and the Subsidiaries have good and
         indefeasible title to all real and personal property necessary to own
         and operate their businesses in all material respects as described in
         the Prospectus, free and clear of all liens, claims, encumbrances and
         defects except (1) as described in the Prospectus and (2) such as do
         not materially interfere with the ownership, operation or benefits of
         ownership of such businesses or materially increase the cost of
         operation or ownership of such businesses, provided that, (a) with
         respect to the Pipeline Properties, the foregoing shall only constitute
         a statement that, to her knowledge, except as described in the
         Prospectus (i) Northern Border Pipeline, Crestone, Bear Paw Energy and
         Midwestern Gas have sufficient title to enable them to use such


                                       23
   24
         Pipeline Properties in their businesses as they have been used in the
         past and are proposed to be used in the future as described in the
         Prospectus and (ii) any lack of title has not had and will not have a
         Material Adverse Effect, and (b) with respect to any real property,
         buildings and equipment held under lease by Northern Border Pipeline,
         Crestone, Bear Paw Energy or Midwestern Gas, such real property,
         buildings and equipment are held by Northern Border Pipeline, and to
         her knowledge, by Crestone, Bear Paw Energy and Midwestern Gas under
         valid, subsisting and enforceable leases with such exceptions as will
         not have a Material Adverse Effect.

               (vii) Each of Northern Border Pipeline, Crestone, Bear Paw
         Investments, Bear Paw Energy, Border Midwestern and Midwestern Gas was
         duly formed (to her knowledge in the case of the latter four entities)
         and is validly existing and in good standing under the laws of its
         jurisdiction of formation and has full corporate, partnership or
         limited liability company power and authority, as the case may be, to
         conduct the activities conducted by it, to own or lease all the assets
         owned or leased by it and to conduct its business as described in the
         Prospectus. Each of Northern Border Pipeline, Crestone, Bear Paw Energy
         and Midwestern Gas is duly licensed or qualified to do business and in
         good standing as a foreign entity in all jurisdictions in which the
         nature of the activities conducted by it or the character of the assets
         owned or leased by it makes such licensing or qualification necessary,
         except for such jurisdictions in which the failure so to qualify or
         register would not have a material adverse effect upon it or subject it
         or the Partnership to any material liability or disability. All of the
         outstanding interests of Northern Border Pipeline have been duly
         authorized and validly issued and are fully paid and non-assessable
         (except as provided in the partnership agreement of Northern Border
         Pipeline). The Intermediate Partnership owns a 70% general partner
         interest in Northern Border Pipeline, and such interest is free and
         clear of any liens, claims or encumbrances (except for such liens,
         encumbrances, security interests, equities, charges or claims as are
         not, individually or in the aggregate, material or except as described
         in the Prospectus). All of the outstanding shares of Crestone have been
         duly authorized and validly issued and are fully paid and
         non-assessable and are owned by the Intermediate Partnership free and
         clear of all liens, claims or encumbrances (except for such liens,
         encumbrances, security interests, equities, charges or claims as are
         not, individually or in the aggregate, material or except as described
         in the Prospectus). All of the outstanding interests of Bear Paw
         Investments have been duly authorized and validly issued and are fully
         paid and non-assessable and are owned by the Intermediate Partnership
         free and clear of any liens, claims or encumbrances (except for such
         liens, encumbrances, security interests, equities, charges or claims as
         are not, individually or in the aggregate, material or except as
         described in the Prospectus). All of the outstanding interests of Bear
         Paw Energy have been duly authorized and validly issued and are fully
         paid and non-assessable and are owned by Bear Paw Investments free and
         clear of any liens, claims or encumbrances (except for such liens,
         encumbrances, security interests, equities, charges or claims as are
         not, individually or in the aggregate, material or except as described
         in the Prospectus). All of the outstanding shares of capital stock of
         Border Midwestern have been duly authorized and validly issued and are
         fully paid and non-assessable and are owned by the Intermediate
         Partnership free and clear of any liens, claims or encumbrances (except
         for such liens, encumbrances, security interests, equities, charges or
         claims as are not, individually or in the aggregate, material or except
         as described in the Prospectus). All of the outstanding shares of
         capital


                                       24
   25
         stock of Midwestern Gas have been duly authorized and validly issued
         and are fully paid and non-assessable and are owned by Border
         Midwestern free and clear of any liens, claims or encumbrances (except
         for such liens, encumbrances, security interests, equities, charges or
         claims as are not, individually or in the aggregate, material or except
         as described in the Prospectus); provided such counsel may qualify to
         her knowledge the opinions (i) as to due authorization, valid issuance,
         full payment and non-assessability with respect to Bear Paw
         Investments, Bear Paw Energy and Midwestern Gas and (ii) as to liens,
         encumbrances and claims enforceable under the UCC with respect to Bear
         Paw Investments and Bear Paw Energy.

         In addition, such counsel shall state that in the course of preparation
     by the Partnership of the Registration Statements, the Preliminary
     Prospectus and the Prospectus, such counsel participated in conferences
     with officers and other representatives of the Partnership and certain of
     the Subsidiaries, representatives of the independent public accountants of
     the Partnership and, in the case of the Preliminary Prospectus and the
     Prospectus, your representatives, at which the contents of the Registration
     Statements, the Preliminary Prospectus and Prospectus and related matters
     were discussed. Such counsel shall also state that although she has not
     conducted any independent investigation with regard to the information set
     forth in the Registration Statements or the Prospectus (except with respect
     to the foregoing opinions) and is not (except as aforesaid) passing upon
     and does not assume any responsibility for the accuracy, completeness or
     fairness of the statements contained therein, on the basis of the foregoing
     and during the course of her representation of Northern Plains, no facts
     have come to such counsel's attention that cause such counsel to believe
     that any of the Registration Statements or any amendment thereto on its
     respective Effective Date, or as amended or supplemented at the Closing
     Date, contained any untrue statement of a material fact or omitted to state
     a material fact required to be stated therein or necessary to make the
     statements therein not misleading, or that, as of its date or the Closing
     Date, the Prospectus or any further amendment or supplement thereto
     contained an untrue statement of a material fact or omitted a material fact
     required to be stated therein or necessary to make the statements therein,
     in light of the circumstances under which they were made, not misleading.
     In making such statement, such counsel may state that she does not express
     any comment with respect to the financial statements and related schedules
     and other financial data included or incorporated by reference in the
     Registration Statements or in the Prospectus or any further amendment or
     supplement thereto (including, without limitation, statements relating to
     projected cash distributions to the limited partners of the Partnership) or
     any statement contained therein or omitted therefrom in reliance upon and
     in conformity with written information furnished to the Partnership by any
     Underwriter through you expressly for use therein.


                                       25
   26
         In rendering such opinion, such counsel may rely (A) as to matters
     involving the application of laws of any jurisdiction other than the State
     of Nebraska, to the extent she deems proper and specified in such opinion,
     upon the opinion of other counsel of good standing whom she believes to be
     reliable and who are satisfactory to counsel for the Underwriters and (B)
     as to matters of fact, to the extent she deems proper, on certificates of
     responsible officers of the Partnership and public officials.

         (d) The Selling Unitholder shall have requested and caused William G.
     von Glahn, General Counsel of the Selling Unitholder, to have furnished to
     the Representatives his opinion dated the Closing Date and addressed to the
     Representatives, to the effect that:

               (i) This Agreement has been duly authorized, executed and
         delivered by the Selling Unitholder and the Selling Unitholder has full
         legal right and authority to sell, transfer and deliver in the manner
         provided in this Agreement the Securities being sold by such Selling
         Unitholder hereunder;

               (ii) no consent, approval, authorization or order of any court or
         governmental agency or body is required for the consummation by the
         Selling Unitholder of the transactions contemplated herein, except such
         as may have been obtained under the Act and such as may be required
         under the blue sky laws of any jurisdiction in connection with the
         purchase and distribution of the Securities by the Underwriters and
         such other approvals (specified in such opinion) as have been obtained;
         and

               (iii) neither the sale of the Securities being sold by the
         Selling Unitholder nor the consummation of any other of the
         transactions herein contemplated by the Selling Unitholder or the
         fulfillment of the terms hereof by the Selling Unitholder will conflict
         with, result in a breach or violation of, or constitute a default under
         (i) the charter or By-laws of the Selling Unitholder or (ii) any law or
         the terms of any indenture or other agreement or instrument known to
         such counsel and to which any Selling Unitholder or any of its
         affiliates is a party or bound, or any judgment, order or decree known
         to such counsel to be applicable to the Selling Unitholder or any of
         its affiliates of any court, regulatory body, administrative agency,
         governmental body or arbitrator having jurisdiction over the Selling
         Unitholder or any of its affiliates, except in the case of clause (ii)
         as would not have a material adverse effect on the Selling Unitholder's
         performance of its obligations hereunder.

         In rendering such opinion, such counsel may state that he is admitted
     to practice law in the States of Oklahoma and New York, and, accordingly,
     the opinions expressed by such counsel, except where expressly further
     limited, will be based upon and limited exclusively to the laws of the
     States of Oklahoma and New York, the General Corporation Law of the State
     of Delaware, and the laws of the United States of America insofar as any of
     such laws are applicable. Such counsel will not be required to render any
     opinion with respect to any other laws.


                                       26
   27
         (e) The Representatives shall have received from Andrews & Kurth
     L.L.P., counsel for the Underwriters, such opinion or opinions, dated the
     Closing Date and addressed to the Representatives, with respect to the
     issuance and sale of the Securities, the Registration Statements, the
     Prospectus (together with any supplement thereto) and other related matters
     as the Representatives may reasonably require, and the Partnership and the
     Selling Unitholder shall have furnished to such counsel such documents as
     they reasonably request for the purpose of enabling them to pass upon such
     matters.

         (f) The Partnership shall have furnished to the Representatives a
     certificate of the Partnership, signed by the Chief Executive Officer and
     the Chief Financial and Accounting Officer of the Partnership, dated the
     Closing Date, to the effect that the signers of such certificate have
     carefully examined each of the Registration Statements, the Prospectus, any
     supplements to the Prospectus and this Agreement and that:

               (i) the representations and warranties of the Partnership and the
         Intermediate Partnership in this Agreement are true and correct in all
         material respects (except that all those representations and warranties
         that are qualified as to their materiality are true and correct in all
         respects) on and as of the Closing Date with the same effect as if made
         on the Closing Date and the Partnership has complied with all the
         agreements and satisfied all the conditions on its part to be performed
         or satisfied at or prior to the Closing Date;

               (ii) no stop order suspending the effectiveness of any of the
         Registration Statements has been issued and no proceedings for that
         purpose have been instituted or, to the Partnership's knowledge,
         threatened; and

               (iii) since the date of the most recent financial statements
         included or incorporated by reference in the Prospectus (exclusive of
         any supplement thereto), there has been no material adverse effect on
         the condition (financial or otherwise), prospects, earnings, business
         or properties of the Partnership and its Subsidiaries, taken as a
         whole, whether or not arising from transactions in the ordinary course
         of business, except as set forth in or contemplated in the Prospectus
         (exclusive of any supplement thereto).

         (g) The Selling Unitholder shall have furnished to the Representatives
     a certificate, signed by an officer of the Selling Unitholder, dated the
     Closing Date, to the effect that the signer of such certificate has
     carefully examined the information relating to the Selling Unitholder in
     the Prospectus, any supplement to the Prospectus and this Agreement and
     that the representations and warranties of the Selling Unitholder in this
     Agreement are true and correct in all material respects on and as of the
     Closing Date to the same effect as if made on the Closing Date.

         (h) The Partnership shall have requested and caused Arthur Andersen LLP
     to have furnished to the Representatives, at the Execution Time and at the
     Closing Date, letters, dated respectively as of the Execution Time and as
     of the Closing Date, in form and substance satisfactory to the
     Representatives, confirming that they are independent accountants within
     the meaning of the Act and the Exchange Act and that they have


                                       27
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     performed a review of the unaudited interim financial information of the
     Partnership for the three-month period ended March 31, 2001 and as of March
     31, 2001 in accordance with Statement on Auditing Standards No. 71, and
     stating in effect that:

               (i) in their opinion the audited financial statements and
         financial statement schedules included or incorporated by reference in
         the Registration Statements and the Prospectus and reported on by them
         comply as to form in all material respects with the applicable
         accounting requirements of the Act and the Exchange Act;

               (ii) on the basis of a reading of the latest unaudited financial
         statements made available by the Partnership and its subsidiaries;
         their limited review, in accordance with standards established under
         Statement on Auditing Standards No. 71, of the unaudited interim
         financial information for the three-month period ended March 31, 2001,
         and as of March 31, 2001, incorporated by reference in the Registration
         Statements and the Prospectus; carrying out certain specified
         procedures (but not an examination in accordance with generally
         accepted auditing standards) which would not necessarily reveal matters
         of significance with respect to the comments set forth in such letter;
         a reading of the minutes of the meetings of the Partnership Policy
         Committee and Audit Committee of the Partnership; and inquiries of
         certain officials of the Partnership who have responsibility for
         financial and accounting matters of the Partnership and its
         subsidiaries as to transactions and events subsequent to December 31,
         2000, nothing came to their attention which caused them to believe
         that:

                    (1) any unaudited financial statements included or
               incorporated by reference in any of the Registration Statements
               and the Prospectus do not comply as to form in all material
               respects with applicable accounting requirements of the Act and
               with the related rules and regulations adopted by the Commission
               with respect to financial statements included or incorporated by
               reference in the Partnership's Quarterly Report on Form 10-Q for
               the quarter ended March 31, 2001 under the Exchange Act; and said
               unaudited financial statements are not in conformity with
               generally accepted accounting principles applied on a basis
               substantially consistent with that of the audited financial
               statements included or incorporated by reference in the
               Registration Statements and the Prospectus;

                    (2) with respect to the period subsequent to March 31, 2001,
               there were any changes, at a specified date not more than five
               days prior to the date of the letter, in the long-term debt
               including current maturities of the Partnership or decreases in
               the partners' capital as compared with the amounts shown on the
               March 31, 2001 consolidated balance sheet included or
               incorporated by reference in any of the Registration Statements
               and the Prospectus, or for the period from April 1, 2001 to such
               specified date there were any decreases, as compared with the
               corresponding period in the preceding quarter in operating
               revenue or net


                                       28
   29
               income to partners, except in all instances for changes or
               decreases set forth in such letter, in which case the letter
               shall be accompanied by an explanation by the Partnership as to
               the significance thereof unless said explanation is not deemed
               necessary by the Representatives; and

                    (3) the information included or incorporated by reference in
               any of the Registration Statements and Prospectus in response to
               Regulation S-K, Item 301 (Selected Financial Data), Item 302
               (Supplementary Financial Information), Item 402 (Executive
               Compensation) and Item 503(d) (Ratio of Earnings to Fixed
               Charges) is not in conformity with the applicable disclosure
               requirements of Regulation S-K;

               (iii) they have performed certain other specified procedures as a
         result of which they determined that certain information of an
         accounting, financial or statistical nature (which is limited to
         accounting, financial or statistical information derived from the
         general accounting records of the Partnership and its subsidiaries) set
         forth in the Registration Statements and the Prospectus and in Exhibit
         12 to each of the Registration Statements, including the information
         set forth under the captions "Selected Historical Consolidated
         Financial Data" in the Prospectus, the information included or
         incorporated by reference in Items 1, 6, 7 and 11 of the Partnership's
         2000 10-K, incorporated by reference in the Registration Statements and
         the Prospectus, and the information included in the "Management's
         Discussion and Analysis of Financial Condition and Results of
         Operations" included or incorporated by reference in the Partnership's
         Quarterly Report on Form 10-Q for the quarter ended March 31, 2001,
         incorporated by reference in the Registration Statements and the
         Prospectus, agrees with the accounting records of the Partnership and
         its subsidiaries, excluding any questions of legal interpretation.

         References to the Prospectus in this paragraph (h) include any
     supplement thereto at the date of the letter.

         (i) Subsequent to the Execution Time or, if earlier, the dates as of
     which information is given in the Registration Statements (exclusive of any
     amendment thereof) and the Prospectus (exclusive of any supplement
     thereto), there shall not have been (i) any change or decrease specified in
     the letter or letters referred to in paragraph (h) of this Section 6 or
     (ii) any change, or any development involving a prospective change, in or
     affecting the condition (financial or otherwise), earnings, business or
     properties of the Partnership and its subsidiaries, taken as a whole,
     whether or not arising from transactions in the ordinary course of
     business, except as set forth in or contemplated in the Prospectus
     (exclusive of any supplement thereto) the effect of which, in any case
     referred to in clause (i) or (ii) above, is, in the sole judgment of the
     Representatives, so material and adverse as to make it impractical or
     inadvisable to proceed with the offering or delivery of the Securities as
     contemplated by the Registration Statements (exclusive of any amendment
     thereof) and the Prospectus (exclusive of any supplement thereto).


                                       29
   30
         (j) Prior to the Closing Date, the Partnership and the Selling
     Unitholder shall have furnished to the Representatives such further
     information, certificates and documents as the Representatives may
     reasonably request.

         (k) The Underwritten Securities issued by the Partnership shall have
     been duly authorized for listing by the New York Stock Exchange, subject to
     official notice of issuance, and satisfactory evidence of such actions
     shall have been provided to the Representatives.

         (l) At the Execution Time, the Partnership shall have furnished to the
     Representatives a letter substantially in the form of Exhibit A hereto
     addressed to the Representatives from Northern Plains, Pan Border, PEC
     Midwest L.L.C. and each officer of the Partnership and member of the
     Partnership Policy Committee who owns Common Units and each of the former
     owners of Bear Paw Investments listed on Schedule III hereto.

         (m) On or prior to the Closing Date, the Partnership shall have
     furnished to the Representatives waivers by each of the General Partners of
     their pre-emptive rights pursuant to Section 4.3 of the Partnership
     Agreement.

         If any of the conditions specified in this Section 6 shall not have
been fulfilled in all material respects when and as provided in this Agreement
or waived by the Representatives in writing, or if any of the opinions and
certificates mentioned above or elsewhere in this Agreement shall not be in all
material respects reasonably satisfactory in form and substance to the
Representatives and counsel for the Underwriters, this Agreement and all
obligations of the Underwriters hereunder may be canceled at, or at any time
prior to, the Closing Date by the Representatives. Notice of such cancellation
shall be given to the Partnership and the Selling Unitholder in writing or by
telephone or facsimile confirmed in writing.

         The documents required to be delivered by this Section 6 shall be
delivered at the office of Andrews & Kurth L.L.P., counsel for the Underwriters,
at 600 Travis Street, Suite 4200, Houston, Texas, 77002, on the Closing Date.

         7. Reimbursement of Underwriters' Expenses. If the sale of the
Securities provided for herein is not consummated because any condition to the
obligations of the Underwriters set forth in Section 6 hereof is not satisfied,
because of any termination pursuant to Section 10 hereof or because of any
refusal, inability or failure on the part of the Partnership or the Selling
Unitholder to perform any agreement herein or comply with any provision hereof
other than by reason of a default by any of the Underwriters, the Partnership
will reimburse the Underwriters severally through Salomon Smith Barney Inc. on
demand for all out-of-pocket expenses (including reasonable fees and
disbursements of counsel) that shall have been incurred by them in connection
with the proposed purchase and sale of the Securities. If the Partnership is
required to make any payments to the Underwriters under this Section 7 because
of the Selling Unitholder's refusal, inability or failure to satisfy any
condition to the obligations of the Underwriters set forth in Section 6, the
Selling Unitholder shall reimburse the Partnership on demand for all amounts so
paid.


                                       30
   31
         8. Indemnification and Contribution. (a) The Partnership agrees to
indemnify and hold harmless each Underwriter, the directors, officers, employees
and agents of each Underwriter and each person who controls any Underwriter
within the meaning of either the Act or the Exchange Act and the Selling
Unitholder, its directors, officers, employees and agents and each person who
controls the Selling Unitholder within the meaning of either the Act or the
Exchange Act against any and all losses, claims, damages or liabilities, joint
or several, to which they or any of them may become subject under the Act, the
Exchange Act or other federal or state statutory law or regulation, at common
law or otherwise, insofar as such losses, claims, damages or liabilities (or
actions in respect thereof) arise out of or are based upon any untrue statement
or alleged untrue statement of a material fact contained in the Registration
Statements as originally filed or in any amendment thereof, or in any
Preliminary Prospectus or the Prospectus, or in any amendment thereof or
supplement thereto, or arise out of or are based upon the omission or alleged
omission to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, and agrees to reimburse
each such indemnified party, as incurred, for any legal or other expenses
reasonably incurred by them in connection with investigating or defending any
such loss, claim, damage, liability or action; provided, however, that the
Partnership will not be liable in any such case to the extent that any such
loss, claim, damage or liability arises out of or is based upon any such untrue
statement or alleged untrue statement or omission or alleged omission made
therein in reliance upon and in conformity with written information furnished to
the Partnership by or on behalf of any Underwriter through the Representatives
specifically for inclusion therein; provided, further, that with respect to any
untrue statement or omission of material fact made in any Preliminary
Prospectus, the indemnity agreement contained in this Section 8(a) shall not
inure to the benefit of any Underwriter from whom the person asserting any such
loss, claim, damage or liability purchased the securities concerned, to the
extent that any such loss, claim, damage or liability of such Underwriter occurs
under the circumstance where it shall have been determined by a court of
competent jurisdiction by final and nonappealable judgment that (w) the
Partnership had previously furnished copies of the Prospectus to the
Representatives, (x) delivery of the Prospectus was required by the Act to be
made to such person, (y) the untrue statement or omission of a material fact
contained in the Preliminary Prospectus was corrected in the Prospectus and (z)
there was not sent or given to such person, at or prior to the written
confirmation of the sale of such securities to such person, a copy of the
Prospectus.

         (b) The Selling Unitholder agrees to indemnify and hold harmless the
Partnership, each member of the Partnership Policy Committee, each officer of
the Partnership who signed the Registration Statements, each Underwriter, the
directors, officers, employees and agents of each Underwriter and each person
who controls the Partnership or any Underwriter within the meaning of either the
Act or the Exchange Act to the same extent as the foregoing indemnity from the
Partnership to each Underwriter, but only with reference to written information
furnished to the Partnership by or on behalf of the Selling Unitholder
specifically for inclusion in the documents referred to in the foregoing
indemnity. This indemnity agreement will be in addition to any liability which
the Selling Unitholder may otherwise have.


                                       31
   32
         (c) Each Underwriter severally and not jointly agrees to indemnify and
     hold harmless the Partnership, each member of the Partnership Policy
     Committee, each officer of the Partnership who signed the Registration
     Statements, and each person who controls the Partnership within the meaning
     of either the Act or the Exchange Act and the Selling Unitholder, its
     directors, officers, employees and agents and each person who controls the
     Selling Unitholder within the meaning of either the Act or the Exchange
     Act, to the same extent as the foregoing indemnity to each Underwriter, but
     only insofar as losses, claims, damages, liabilities or actions arise out
     of or are based upon any untrue statement or omission or alleged untrue
     statement or omission made in reliance on and in conformity with written
     information relating to such Underwriter furnished to the Partnership by or
     on behalf of such Underwriter through the Representatives specifically for
     inclusion in the documents referred to in the foregoing indemnity. This
     indemnity agreement will be in addition to any liability which any
     Underwriter may otherwise have. The Partnership and the Selling Unitholder
     acknowledge that the statements set forth in the last paragraph of the
     cover page regarding delivery of the Securities and, under the heading
     "Underwriting," (i) the table setting forth the names of the underwriters
     and the number of common units sold to each of them, (ii) the sentences
     related to concessions and reallowances and (iii) the paragraph(s) related
     to stabilization, syndicate covering transactions and penalty bids and the
     effect of such practices in any Preliminary Prospectus and the Prospectus
     constitute the only information furnished in writing by or on behalf of the
     several Underwriters for inclusion in any Preliminary Prospectus or the
     Prospectus.

         (d) Promptly after receipt by an indemnified party under this Section 8
     of notice of the commencement of any action, such indemnified party will,
     if a claim in respect thereof is to be made against the indemnifying party
     under this Section 8, notify the indemnifying party in writing of the
     commencement thereof; but the failure so to notify the indemnifying party
     (i) will not relieve it from liability under paragraph (a), (b) or (c)
     above unless and to the extent it did not otherwise learn of such action
     and such failure results in the forfeiture by the indemnifying party of
     substantial rights and defenses and (ii) will not, in any event, relieve
     the indemnifying party from any obligations to any indemnified party other
     than the indemnification obligation provided in paragraph (a), (b) or (c)
     above. The indemnifying party shall be entitled to appoint counsel of the
     indemnifying party's choice at the indemnifying party's expense to
     represent the indemnified party in any action for which indemnification is
     sought (in which case the indemnifying party shall not thereafter be
     responsible for the fees and expenses of any separate counsel retained by
     the indemnified party or parties except as set forth below); provided,
     however, that such counsel shall be satisfactory to the indemnified party.
     Notwithstanding the indemnifying party's election to appoint counsel to
     represent the indemnified party in an action, the indemnified party shall
     have the right to employ separate counsel (including local counsel), and
     the indemnifying party shall bear the reasonable fees, costs and expenses
     of such separate counsel if (i) the use of counsel chosen by the
     indemnifying party to represent the indemnified party would present such
     counsel with a conflict of interest, (ii) the actual or potential
     defendants in, or targets of, any such action include both the indemnified
     party and the indemnifying party and the indemnified party shall have
     reasonably concluded that there may be legal defenses


                                       32
   33
     available to it and/or other indemnified parties which are different from
     or additional to those available to the indemnifying party, (iii) the
     indemnifying party shall not have employed counsel satisfactory to the
     indemnified party to represent the indemnified party within a reasonable
     time after notice of the institution of such action or (iv) the
     indemnifying party shall authorize the indemnified party to employ separate
     counsel at the expense of the indemnifying party. An indemnifying party
     will not, without the prior written consent of the indemnified parties,
     settle or compromise or consent to the entry of any judgment with respect
     to any pending or threatened claim, action, suit or proceeding in respect
     of which indemnification or contribution may be sought hereunder (whether
     or not the indemnified parties are actual or potential parties to such
     claim or action) unless such settlement, compromise or consent includes an
     unconditional release of each indemnified party from all liability arising
     or that may arise out of such claim, action, suit or proceeding.

         (e) In the event that the indemnity provided in paragraph (a), (b) or
     (c) of this Section 8 is unavailable to or insufficient to hold harmless an
     indemnified party for any reason, the Partnership, the Selling Unitholder
     and the Underwriters agree to contribute to the aggregate losses, claims,
     damages and liabilities (including legal or other expenses reasonably
     incurred in connection with investigating or defending same) (collectively
     "Losses") to which the Partnership, the Selling Unitholder and one or more
     of the Underwriters may be subject in such proportion as is appropriate to
     reflect the relative benefits received by the Partnership, by the Selling
     Unitholder and by the Underwriters from the offering of the Securities;
     provided, however, that in no case shall any Underwriter (except as may be
     provided in any agreement among underwriters relating to the offering of
     the Securities) be responsible for any amount in excess of the underwriting
     discount or commission applicable to the Securities purchased by such
     Underwriter hereunder. If the allocation provided by the immediately
     preceding sentence is unavailable for any reason, the Partnership, the
     Selling Unitholder and the Underwriters shall contribute in such proportion
     as is appropriate to reflect not only such relative benefits but also the
     relative fault of the Partnership, of the Selling Unitholder and of the
     Underwriters in connection with the statements or omissions which resulted
     in such Losses as well as any other relevant equitable considerations.
     Benefits received by the Partnership and by the Selling Unitholder shall be
     deemed to be equal to the total net proceeds from the offering (before
     deducting expenses) received by each of them, and benefits received by the
     Underwriters shall be deemed to be equal to the total underwriting
     discounts and commissions, in each case as set forth on the cover page of
     the Prospectus. Relative fault shall be determined by reference to, among
     other things, whether any untrue or any alleged untrue statement of a
     material fact or the omission or alleged omission to state a material fact
     relates to information provided by the Partnership or the Selling
     Unitholder, on the one hand, or the Underwriters, on the other, the intent
     of the parties and their relative knowledge, access to information and
     opportunity to correct or prevent such untrue statement or omission. The
     Partnership, the Selling Unitholder and the Underwriters agree that it
     would not be just and equitable if contribution were determined by pro rata
     allocation or any other method of allocation which does not take account of
     the equitable considerations referred to above. Notwithstanding the
     provisions of this paragraph (e), no person guilty of fraudulent
     misrepresentation (within the meaning of Section 11(f) of the Act) shall be
     entitled to


                                       33
   34
     contribution from any person who was not guilty of such fraudulent
     misrepresentation. For purposes of this Section 8, each person who controls
     an Underwriter within the meaning of either the Act or the Exchange Act and
     each director, officer, employee and agent of an Underwriter shall have the
     same rights to contribution as such Underwriter, each person who controls
     the Partnership within the meaning of either the Act or the Exchange Act,
     each officer of the Partnership who signed the Registration Statements and
     each member of the Partnership Policy Committee shall have the same rights
     to contribution as the Partnership, and each person who controls the
     Selling Unitholder within the meaning of either the Act or the Exchange Act
     and each officer, director, employee and agent of the Selling Unitholder
     shall have the same rights to contribution as the Selling Unitholder,
     subject in each case to the applicable terms and conditions of this
     paragraph (e).

         9. Default by an Underwriter. If any one or more Underwriters shall
fail to purchase and pay for any of the Securities agreed to be purchased by
such Underwriter or Underwriters hereunder and such failure to purchase shall
constitute a default in the performance of its or their obligations under this
Agreement, the remaining Underwriters shall be obligated severally to take up
and pay for (in the respective proportions which the amount of Securities set
forth opposite their names in Schedule I hereto bears to the aggregate amount of
Securities set forth opposite the names of all the remaining Underwriters) the
Securities which the defaulting Underwriter or Underwriters agreed but failed to
purchase; provided, however, that in the event that the aggregate amount of
Securities which the defaulting Underwriter or Underwriters agreed but failed to
purchase shall exceed 10% of the aggregate amount of Securities set forth in
Schedule I hereto, the remaining Underwriters shall have the right to purchase
all, but shall not be under any obligation to purchase any, of the Securities,
and if such nondefaulting Underwriters do not purchase all the Securities, this
Agreement will terminate without liability to any nondefaulting Underwriter, the
Selling Unitholder or the Partnership. In the event of a default by any
Underwriter as set forth in this Section 9, the Closing Date shall be postponed
for such period, not exceeding five Business Days, as the Representatives shall
determine in order that the required changes in the Registration Statements and
the Prospectus or in any other documents or arrangements may be effected.
Nothing contained in this Agreement shall relieve any defaulting Underwriter of
its liability, if any, to the Partnership, the Selling Unitholder and any
nondefaulting Underwriter for damages occasioned by its default hereunder.

         10. Termination. This Agreement shall be subject to termination in the
absolute discretion of the Representatives, by notice given to the Partnership
prior to delivery of and payment for the Securities, if at any time prior to
such time (i) trading in the Partnership's Common Units shall have been
suspended by the Commission or the New York Stock Exchange or trading in
securities generally on the New York Stock Exchange shall have been suspended or
limited or minimum prices shall have been established on such Exchange, (ii) a
banking moratorium shall have been declared either by federal or New York State
authorities or (iii) there shall have occurred any outbreak or escalation of
hostilities, declaration by the United States of a national emergency or war, or
other calamity or crisis the effect of which on financial markets is such as to
make it, in the sole judgment of the Representatives, impractical or inadvisable
to proceed with the offering or delivery of the Securities as contemplated by
the Prospectus (exclusive of any supplement thereto).


                                       34
   35
         11. Representations and Indemnities to Survive. The respective
agreements, representations, warranties, indemnities and other statements of the
Partnership or its officers, of the Selling Unitholder and of the Underwriters
set forth in or made pursuant to this Agreement will remain in full force and
effect, regardless of any investigation made by or on behalf of any Underwriter,
the Selling Unitholder or the Partnership or any of the officers, directors,
employees, agents or controlling persons referred to in Section 8 hereof, and
will survive delivery of and payment for the Securities. The provisions of
Sections 7 and 8 hereof shall survive the termination or cancellation of this
Agreement.

         12. Notices. All communications hereunder will be in writing and
effective only on receipt, and, if sent to the Representatives, will be mailed,
delivered or telefaxed to the Salomon Smith Barney Inc. General Counsel (fax
no.: (212) 816-7912) and confirmed to the General Counsel, Salomon Smith Barney
Inc., at 388 Greenwich Street, New York, New York, 10013, Attention: General
Counsel; or, if sent to the Partnership, will be mailed, delivered or telefaxed
to Janet K. Place at (402) 398-7780 and confirmed to her at (402) 398-7886; or
if sent to the Selling Unitholder, will be mailed, delivered or telefaxed and
confirmed to it at the address set forth in Schedule II hereto.

         13. Successors. This Agreement will inure to the benefit of and be
binding upon the parties hereto and their respective successors and the
officers, directors, employees, agents and controlling persons referred to in
Section 8 hereof, and no other person will have any right or obligation
hereunder.

         14. Applicable Law. This Agreement will be governed by and construed in
accordance with the laws of the State of New York applicable to contracts made
and to be performed within the State of New York.

         15. Counterparts. This Agreement may be signed in one or more
counterparts, each of which shall constitute an original and all of which
together shall constitute one and the same agreement.

         16. Headings. The section headings used herein are for convenience only
and shall not affect the construction hereof.

         17. Definitions. The terms which follow, when used in this Agreement,
shall have the meanings indicated.

         "Act" shall mean the Securities Act of 1933, as amended, and the rules
     and regulations of the Commission promulgated thereunder.

         "Business Day" shall mean any day other than a Saturday, a Sunday or a
     legal holiday or a day on which banking institutions or trust companies are
     authorized or obligated by law to close in New York City.

         "Commission" shall mean the Securities and Exchange Commission.

         "Effective Date" shall mean, with respect to each of the Registration
     Statements, each date and time that such Registration Statement, any
     post-effective amendment or


                                       35
   36
     amendments thereto and any Rule 462(b) Registration Statement became or
     become effective.

         "Exchange Act" shall mean the Securities Exchange Act of 1934, as
     amended, and the rules and regulations of the Commission promulgated
     thereunder.

         "Execution Time" shall mean the date and time that this Agreement is
     executed and delivered by the parties hereto.

         "Preliminary Prospectus" shall mean any preliminary prospectus
     supplement to the base prospectuses included in each of the Registration
     Statements at their respective Effective Dates, together with such base
     prospectuses, that describes the Securities and the offering thereof, that
     is filed pursuant to Rule 424(b) and that is used prior to the filing of
     the Prospectus.

         "Prospectus" shall mean the final prospectus supplement to the base
     prospectuses included in each of the Registration Statements at their
     respective Effective Dates, together with such base prospectuses, that
     describes the Securities and the offering thereof, and that is first filed
     pursuant to Rule 424(b) after the Execution Time.

         "Registration Statements" shall mean each of the three registration
     statements referred to in paragraph 1(i)(a) above, including exhibits and
     financial statements, as amended at the Execution Time (or, if not
     effective at the Execution Time, in the form in which it shall become
     effective) and, in the event any post-effective amendment thereto or any
     Rule 462(b) Registration Statement becomes effective prior to the Closing
     Date, shall also mean such registration statement as so amended or such
     Rule 462(b) Registration Statement, as the case may be. Such term shall
     include any Rule 430A Information deemed to be included therein at the
     Effective Date as provided by Rule 430A.

         "Rule 424", "Rule 430A" and "Rule 462" refer to such rules under the
     Act.

         "Rule 430A Information" shall mean information with respect to the
     Securities and the offering thereof permitted to be omitted from the
     Registration Statement when it becomes effective pursuant to Rule 430A.

         "Rule 462(b) Registration Statement" shall mean a registration
     statement and any amendments thereto filed pursuant to Rule 462(b) relating
     to the offering covered by the registration statements referred to in
     Section 1(a) hereof.

         "Subsidiary" shall mean the Intermediate Partnership, Northern Border
     Pipeline, Crestone, Bear Paw Investments, Bear Paw Energy, Border
     Midwestern and Midwestern Gas.


                                       36
   37
         If the foregoing is in accordance with your understanding of our
agreement, please sign and return to us the enclosed duplicate hereof, whereupon
this letter and your acceptance shall represent a binding agreement among the
Partnership, the Intermediate Partnership, the Selling Unitholder and the
several Underwriters.


                                Very truly yours,

                                Northern Border Partners, L.P.



                                By:   /s/ JERRY L. PETERS
                                     -------------------------------------------
                                Name:   Jerry L. Peters
                                       -----------------------------------------
                                Title:   Chief Financial and Accounting Officer
                                        ----------------------------------------


                                Northern Border Intermediate Limited Partnership

                                By:   /s/ WILLIAM R. CORDES
                                     -------------------------------------------
                                Name:   William R. Cordes
                                       -----------------------------------------
                                Title:   Chief Executive Officer
                                        ----------------------------------------


                                Northwest Border Pipeline Company

                                By:   /s/ JAMES C. MOORE
                                     -------------------------------------------
                                Name:   James C. Moore
                                       -----------------------------------------
                                Title:   Vice President
                                        ----------------------------------------


                                       37
   38
The foregoing Agreement is hereby
confirmed and accepted as of the
date first above written.

Salomon Smith Barney Inc.
Banc of America Securities LLC
UBS Warburg LLC
A.G. Edwards & Sons, Inc.
Dain Rauscher Incorporated
First Union Securities, Inc.

By:  Salomon Smith Barney Inc.

By:    /s/ JOHN A. CIOLEK
     --------------------------
Name:      John A. Ciolek
       ------------------------
Title:     Director
        -----------------------

For themselves and the other
several Underwriters named in
Schedule I to the foregoing
Agreement.


                                       38
   39
                                   SCHEDULE I




                                                                         NUMBER OF UNDERWRITTEN
UNDERWRITERS                                                           SECURITIES TO BE PURCHASED
- ------------                                                           --------------------------
                                                                    
Salomon Smith Barney Inc.......................................                1,225,209

UBS Warburg LLC...............................................                 1,225,209

Banc of America Securities LLC................................                   556,900

A. G. Edwards & Sons, Inc.....................................                   556,900

Dain Rauscher Incorporated....................................                   445,500

First Union Securities, Inc...................................                   445,500
                                                                               ---------
Total                                                                          4,455,218
                                                                               =========



                                  Schedule I-1
   40
                                   SCHEDULE II




                                                                                                  MAXIMUM NUMBER OF
                                                             NUMBER OF UNDERWRITTEN               OPTION SECURITIES
SELLING UNITHOLDER:                                          SECURITIES TO BE SOLD                   TO BE SOLD
- ------------------                                           ----------------------               -----------------
                                                                                            
Northwest Border Pipeline Company
295 Chipeta Way
Salt Lake City, Utah 84108........................                  455,218                           668, 282

with copies to:

The Williams Companies, Inc.
One Williams Center, Suite 4900
Tulsa, Oklahoma  74172
Attention:  Cuba Wadlington
Facsimile:  918.573.7427

The Williams Companies, Inc.
P.O. Box 1396
Houston, Texas  77251
Attention:  James Moore
Facsimile:  713.215.4269

                                                                -----------                        -----------
     Total........................................                  455,218                            668,282
                                                                ===========                        ===========



                                  Schedule II-1
   41
                                  SCHEDULE III


1. Cub Investment, LLC
2. Haddington / Chase Energy Partners (Bear Paw) LP
3. Cleveptnrs
4. Thomas Edelman
5. Robert Clark
6. Michael Henderson
7. Pierce Norton
8. Carl Holmgren
9. Richard VandeBossche
10. Bruce Duval
11. Jonathon Nixon
12. Thom. Edelman Irrevocable Trust fbo Eliz. Edelman
13. Thom. Edelman Irrevicable Trust fbo Eleanor Edelman
14. R&K Ventures, LLP
15. Bear Cub Investments, LLC


                                       2
   42
                                                                       EXHIBIT A


      [LETTERHEAD OF OFFICER, DIRECTOR OR MAJOR STOCKHOLDER OF CORPORATION]


                         Northern Border Partners, L.P.
                         Public Offering of Common Units


                                                                   May ___, 2001


Salomon Smith Barney Inc.
Banc of America Securities LLC
UBS Warburg LLC
A.G. Edwards & Sons, Inc.
Dain Rauscher Incorporated
First Union Securities, Inc.
As Representatives of the several Underwriters,
c/o Salomon Smith Barney Inc.
388 Greenwich Street
New York, New York 10013

Ladies and Gentlemen:

         This letter is being delivered to you in connection with the proposed
Underwriting Agreement (the "Underwriting Agreement"), between Northern Border
Partners, L.P., a Delaware limited partnership (the "Partnership"), Northwest
Border Pipeline Company, a Delaware corporation, and each of you as
representatives of a group of Underwriters named therein, relating to an
underwritten public offering of Common Units (the "Common Units"), of the
Partnership.

         In order to induce you and the other Underwriters to enter into the
Underwriting Agreement, the undersigned will not, without the prior written
consent of Salomon Smith Barney Inc., offer, sell, contract to sell, pledge or
otherwise dispose of, (or enter into any transaction which is designed to, or
might reasonably be expected to, result in the disposition (whether by actual
disposition or effective economic disposition due to cash settlement or
otherwise) by the undersigned or any affiliate of the undersigned or any person
in privity with the undersigned or any affiliate of the undersigned), directly
or indirectly, including the filing (or participation in the filing) of a
registration statement with the Securities and Exchange Commission in respect
of, or establish or increase a put equivalent position or liquidate or decrease
a call equivalent position within the meaning of Section 16 of the Securities
Exchange Act of 1934, as amended, and the rules and regulations of the
Securities and Exchange Commission promulgated thereunder with respect to, any
Common Units of the Partnership or any securities convertible into, or
exercisable or exchangeable for such Common Units, or publicly announce an
intention to effect any such transaction, for a period of ninety (90) days after
the date of this Agreement, other than Common Units disposed of as bona fide
gifts approved by Salomon Smith Barney Inc.

   43
         If for any reason the Underwriting Agreement shall be terminated prior
to the Closing Date (as defined in the Underwriting Agreement), the agreement
set forth above shall likewise be terminated.


                                        Yours very truly,

                                        [SIGNATURE OF OFFICER, DIRECTOR OR
                                        MAJOR STOCKHOLDER]

                                        [NAME AND ADDRESS OF OFFICER, DIRECTOR
                                        OR MAJOR STOCKHOLDER]