CERTIFICATE OF DESIGNATIONS

                               of

                    SERIES B PREFERENCE STOCK

                               of

                    MDU RESOURCES GROUP, INC.


                 (Pursuant to Section 151 of the
                Delaware General Corporation Law)

     MDU Resources Group, Inc., a corporation organized and
existing under the General Corporation Law of the State of
Delaware (hereinafter called the "Corporation"), hereby certifies
that the following resolution was adopted by the Board of
Directors of the Corporation as required by Section 151 of the
General Corporation Law at a meeting duly called and held on
August 15, 2002:

          WHEREAS, on November 12, 1998, the Board of Directors
     created a new series of Preference Stock, without par value,
     of the Company to be designated the Series B Preference
     Stock, (the "Series B Preference Stock"), authorized 60,000
     shares of Series B Preference Stock, and fixed the relative
     rights, preferences and limitations thereof (in addition to
     the provisions set forth in the Restated Certificate of
     Incorporation of the Company, which are applicable to the
     Preference Stock); and the Board of Directors of the
     Corporation approved a Certificate of Designations for the
     Series B Preference Stock (the "1998 Certificate of
     Designations"), which sets forth the powers, designations,
     preferences and relative rights, and the qualifications,
     limitations, or restrictions thereof, and the 1998
     Certificate of Designations was filed with the Secretary of
     State of Delaware on November 13, 1998; and

          WHEREAS, the Board of Directors desires to increase the
     number of shares authorized under the 1998 Certificate of
     Designations to 125,000;

          NOW, THEREFORE, BE IT RESOLVED, that pursuant to the
     authority granted to and vested in the Board of Directors of
     MDU Resources Group, Inc. (the "Corporation") in accordance
     with the provisions of the Restated Certificate of
     Incorporation, the Board of Directors hereby approves the
     Certificate of Designations of Series B Preference Stock of
     the Company, as amended and restated, which designates the
     Series B Preference Stock, establishes the number of shares
     for the Series B Preference Stock, and fixes the
     preferences, relative rights, and limitations thereof (in
     addition to the provisions set forth in the Restated
     Certificate of Incorporation of the Company, which are
     applicable to the Preference Stock) as follows:

     Series B Preference Stock:

     Section 1.  Designation and Amount.  The shares of such
series shall be designated as "Series B Preference Stock" (the
"Series B Preference Stock") and the number of shares
constituting the Series B Preference Stock shall be 125,000.
Such number of shares may be increased or decreased by resolution
of the Board of Directors; provided, that no decrease shall
reduce the number of shares of Series B Preference Stock to a
number less than the number of shares then outstanding plus the
number of shares reserved for issuance upon the exercise of
outstanding options, rights or warrants or upon the conversion of
any outstanding securities issued by the Corporation convertible
into Series B Preference Stock.

     Section 2.  Dividends and Distributions.

          (A)  Subject to the rights of the holders of any shares
     of any series of Preferred Stock or Preferred Stock A (or
     any similar stock) ranking prior and superior to the
     Series B Preference Stock with respect to dividends, the
     holders of shares of Series B Preference Stock, equally with
     holders of all other series of Preference Stock and in
     preference to the holders of Common Stock, par value $1.00
     per share (the "Common Stock"), of the Corporation, and of
     any other junior stock, shall be entitled to receive, when,
     as and if declared by the Board of Directors out of funds
     legally available for the purpose, quarterly dividends
     payable in cash on the first day of January, April, July,
     and October in each year (each such date being referred to
     herein as a "Quarterly Dividend Payment Date"), commencing
     on the first Quarterly Dividend Payment Date after the first
     issuance of a share or fraction of a share of Series B
     Preference Stock, in an amount per share (rounded to the
     nearest cent) equal to the greater of (a) $1.00 or (b)
     subject to the provision for adjustment hereinafter set
     forth, 1,000 times the aggregate per share amount of all
     cash dividends, and 1,000 times the aggregate per share
     amount (payable in kind) of all non-cash dividends or other
     distributions, other than a dividend payable in shares of
     Common Stock or a subdivision of the outstanding shares of
     Common Stock (by reclassification or otherwise), declared on
     the Common Stock since the immediately preceding Quarterly
     Dividend Payment Date or, with respect to the first
     Quarterly Dividend Payment Date, since the first issuance of
     any share or fraction of a share of Series B Preference
     Stock.  In the event the Corporation shall at any time
     declare or pay any dividend on the Common Stock payable in
     shares of Common Stock, or effect a subdivision or
     combination or consolidation of the outstanding shares of
     Common Stock (by reclassification or otherwise than by
     payment of a dividend in shares of Common Stock) into a
     greater or lesser number of shares of Common Stock, then in
     each such case the amount to which holders of shares of
     Series B Preference Stock were entitled immediately prior to
     such event under clause (b) of the preceding sentence shall
     be adjusted by multiplying such amount by a fraction, the
     numerator of which is the number of shares of Common Stock
     outstanding immediately after such event and the denominator
     of which is the number of shares of Common Stock that were
     outstanding immediately prior to such event.

          (B)  The Corporation shall declare a dividend or
     distribution on the Series B Preference Stock as provided in
     paragraph (A) of this Section immediately after it declares
     a dividend or distribution on the Common Stock (other than a
     dividend payable in shares of Common Stock); provided that,
     in the event no dividend or distribution shall have been
     declared on the Common Stock during the period between any
     Quarterly Dividend Payment Date and the next subsequent
     Quarterly Dividend Payment Date, a dividend of $1.00 per
     share on the Series B Preference Stock shall nevertheless be
     payable on such subsequent Quarterly Dividend Payment Date.

          (C)  Dividends shall begin to accrue and be cumulative
     on outstanding shares of Series B Preference Stock from the
     Quarterly Dividend Payment Date next preceding the date of
     issue of such shares, unless the date of issue of such
     shares is prior to the record date for the first Quarterly
     Dividend Payment Date, in which case dividends on such
     shares shall begin to accrue from the date of issue of such
     shares, or unless the date of issue is a Quarterly Dividend
     Payment Date or is a date after the record date for the
     determination of holders of shares of Series B Preference
     Stock entitled to receive a quarterly dividend and before
     such Quarterly Dividend Payment Date, in either of which
     events such dividends shall begin to accrue and be
     cumulative from such Quarterly Dividend Payment Date.
     Accrued but unpaid dividends shall not bear interest.
     Dividends paid on the shares of Series B Preference Stock in
     an amount less than the total amount of such dividends at
     the time accrued and payable on such shares shall be
     allocated pro rata on a share-by-share basis among all such
     shares at the time outstanding.  The Board of Directors may
     fix a record date for the determination of holders of shares
     of Series B Preference Stock entitled to receive payment of
     a dividend or distribution declared thereon, which record
     date shall be not more than 60 days prior to the date fixed
     for the payment thereof.

     Section 3.  Voting Rights.  The holders of shares of
Series B Preference Stock shall have no voting rights except as
otherwise provided by law or as set forth in the Corporation's
Certificate of Incorporation.

     Section 4.  Certain Restrictions.

          (A)  Whenever quarterly dividends or other dividends or
     distributions payable on the Series B Preference Stock as
     provided in Section 2 are in arrears, thereafter and until
     all accrued and unpaid dividends and distributions, whether
     or not declared, on shares of Series B Preference Stock
     outstanding shall have been paid in full, the Corporation
     shall not:

               (i)   declare or pay dividends, or make any other
          distributions, on any shares of stock ranking junior
          (either as to dividends or upon liquidation,
          dissolution, or winding up) to the Series B Preference
          Stock;

               (ii)  declare or pay dividends, or make any other
          distributions, on any shares of stock ranking on a
          parity (either as to dividends or upon liquidation,
          dissolution, or winding up) with the Series B
          Preference Stock, except dividends paid ratably on the
          Series B Preference Stock and all such parity stock on
          which dividends are payable or in arrears in proportion
          to the total amounts to which the holders of all such
          shares are then entitled;

               (iii) redeem or purchase or otherwise acquire
          for consideration shares of any stock ranking junior
          (either as to dividends or upon liquidation,
          dissolution, or winding up) to the Series B Preference
          Stock, provided that the Corporation may at any time
          redeem, purchase or otherwise acquire shares of any
          such junior stock in exchange for shares of any stock
          of the Corporation ranking junior (either as to
          dividends or upon dissolution, liquidation or winding
          up) to the Series B Preference Stock; or

               (iv) redeem or purchase or otherwise acquire for
          consideration any shares of Series B Preference Stock,
          or any shares of stock ranking on a parity with the
          Series B Preference Stock, except in accordance with a
          purchase offer made in writing or by publication (as
          determined by the Board of Directors) to all holders of
          such shares upon such terms as the Board of Directors,
          after consideration of the respective annual dividend
          rates and other relative rights and preferences of the
          respective series and classes, shall determine in good
          faith will result in fair and equitable treatment among
          the respective series or classes.

          (B)  The Corporation shall not permit any subsidiary of
     the Corporation to purchase or otherwise acquire for
     consideration any shares of stock of the Corporation unless
     the Corporation could, under paragraph (A) of this
     Section 4, purchase or otherwise acquire such shares at such
     time and in such manner.

     Section 5.  Reacquired Shares.  Any shares of Series B
Preference Stock purchased or otherwise acquired by the
Corporation in any manner whatsoever shall be retired and
cancelled promptly after the acquisition thereof.  All such
shares shall upon their cancellation become authorized but
unissued shares of Preference Stock and may be reissued as part
of a new series of Preference Stock subject to the conditions and
restrictions on issuance set forth herein, in the Certificate of
Incorporation, or in any other Certificate of Designations
creating a series of Preference Stock or any similar stock or as
otherwise required by law.

     Section 6.  Liquidation, Dissolution, or Winding Up.  Upon
any liquidation, dissolution, or winding up of the Corporation,
no distribution shall be made (1) to the holders of shares of
stock ranking junior (either as to dividends or upon liquidation,
dissolution, or winding up) to the Series B Preference Stock
unless, prior thereto, the holders of shares of Series B
Preference Stock shall have received $1,000 per share, plus an
amount equal to accrued and unpaid dividends and distributions
thereon, whether or not declared, to the date of such payment,
provided that the holders of shares of Series B Preference Stock
shall be entitled to receive an aggregate amount per share,
subject to the provision for adjustment hereinafter set forth,
equal to 1,000 times the aggregate amount to be distributed per
share to holders of shares of Common Stock, or (2) to the holders
of shares of stock ranking on a parity (either as to dividends or
upon liquidation, dissolution, or winding up) with the Series B
Preference Stock, except distributions made ratably on the
Series B Preference Stock and all such parity stock in proportion
to the total amounts to which the holders of all such shares are
entitled upon such liquidation, dissolution, or winding up.  In
the event the Corporation shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock,
or effect a subdivision or combination or consolidation of the
outstanding shares of Common Stock (by reclassification or
otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock,
then in each such case the aggregate amount to which holders of
shares of Series B Preference Stock were entitled immediately
prior to such event under the proviso in clause (1) of the
preceding sentence shall be adjusted by multiplying such amount
by a fraction the numerator of which is the number of shares of
Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that
were outstanding immediately prior to such event.

     Section 7.  Consolidation, Merger, etc.  In case the
Corporation shall enter into any consolidation, merger,
combination, or other transaction in which the shares of Common
Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case
each share of Series B Preference Stock shall at the same time be
similarly exchanged or changed into an amount per share, subject
to the provision for adjustment hereinafter set forth, equal to
1,000 times the aggregate amount of stock, securities, cash
and/or any other property (payable in kind), as the case may be,
into which or for which each share of Common Stock is changed or
exchanged.  In the event the Corporation shall at any time
declare or pay any dividend on the Common Stock payable in shares
of Common Stock, or effect a subdivision or combination or
consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in
shares of Common Stock) into a greater or lesser number of shares
of Common Stock, then in each such case the amount set forth in
the preceding sentence with respect to the exchange or change of
shares of Series B Preference Stock shall be adjusted by
multiplying such amount by a fraction, the numerator of which is
the number of shares of Common Stock outstanding immediately
after such event and the denominator of which is the number of
shares of Common Stock that were outstanding immediately prior to
such event.

     Section 8.  No Redemption.  The shares of Series B
Preference Stock shall not be redeemable.

     Section 9.  Rank.  The Series B Preference Stock shall rank,
with respect to the payment of dividends and the distribution of
assets, junior to all series of any class of the Corporation's
Preferred Stock and Preferred Stock A, shall rank equally with
all other series of the Corporation's Preference Stock, and shall
rank superior to the Common Stock and any other class or series
of junior stock.

     Section 10.  Amendment.  The Certificate of Incorporation of
the Corporation shall not be amended in any manner which would
materially alter or change the powers, preferences, or special
rights of the Series B Preference Stock so as to affect them
adversely without the affirmative vote of the holders of at least
a majority of the outstanding shares of Series B Preference
Stock, voting together as a single class.

     IN WITNESS WHEREOF, this Certificate of Designations is
executed on behalf of the Corporation by its President and Chief
Executive Officer and attested by its Secretary on August 15,
2002.

                         MDU RESOURCES GROUP, INC.
ATTEST:

/s/LESTER H. LOBLE, II   By: /s/ MARTIN A. WHITE
Lester H. Loble, II         Martin A. White
Secretary                   President and Chief Executive Officer