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                                                                       EXHIBIT 5



                     [UNION PACIFIC CORPORATION LETTERHEAD]



Richard J. Ressler
Assistant General Counsel


                                                              December 20, 1996

Union Pacific Corporation
Eighth and Eaton Avenues
Bethlehem, PA  18018

         RE:        UNION PACIFIC CORPORATION $1,000,000,000 AGGREGATE
                    PUBLIC OFFERING PRICE OF OFFERED SECURITIES

Dear Sirs:

         I am Assistant General Counsel of Union Pacific Corporation, a Utah
corporation (the "Company"), and I am rendering this opinion in connection with
the Company's Registration Statement on Form S-3 (the "Registration Statement")
being filed today with the Securities and Exchange Commission under the
Securities Act of 1933, as amended (the "Act"), with respect to the Company's
debt securities (the "Debt Securities"), preferred stock, with no par value (the
"Preferred Stock"), warrants to purchase Debt Securities and Preferred Stock
(the "Warrants"), and common stock, par value $2.50 per share, (the "Common
Stock") issuable upon conversion or exchange of Debt Securities or Preferred
Stock (the Debt Securities, Preferred Stock, Warrants and Common Stock are
collectively referred to as the "Offered Securities"), for issuance from time to
time pursuant to Rule 415 under the Act.

         I have examined the form of Indenture (the "Indenture") between the
Company and Citibank, N.A., as trustee (the "Trustee"), pursuant to which the
Debt Securities will be issued, and I have examined such other documents and
made such other investigations as I have deemed necessary or advisable for
purposes of this opinion. Based thereon, I am of the opinion that:

         1. The Company is a corporation duly organized and validly existing
under the laws of the State of Utah.

         2. The execution and delivery of the Indenture by the Company and the
issuance and sale of Debt Securities have been validly authorized by all
necessary corporate action by the Company.

         3. When (i) the Registration Statement shall have become effective
under the Act, (ii) the Blue Sky or securities laws of certain states shall have
been complied with, (iii) the Indenture shall have been executed and delivered
by the Company and the Trustee and duly qualified under the Trust Indenture Act
of 1939, and (iv) the Debt Securities shall have been (A) duly authorized,
executed, authenticated and delivered against

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payment therefor or (B) issued upon conversion or exchange of Debt Securities or
Preferred Stock which, by their respective terms, are convertible into or
exchangeable for Debt Securities or upon exercise of Warrants, and the Company
shall have received any additional consideration which is payable upon such
conversion, exchange or exercise, the Debt Securities shall constitute binding
obligations of the Company enforceable in accordance with their terms, except as
enforceability may be limited by bankruptcy, insolvency, reorganization or other
laws relating to or affecting creditors' rights generally and subject to general
principles of equity.

         4. When (i) the Registration Statement shall have become effective
under the Act, (ii) the Blue Sky or securities laws of certain states shall have
been complied with, and (iii) the Preferred Stock shall have been (A)
authorized, issued and sold as contemplated by the Registration Statement and
the Company shall have received consideration therefor or (B) issued upon
conversion or exchange of Debt Securities or Preferred Stock which, by their
respective terms, are convertible into or exchangeable for shares of Preferred
Stock or upon exercise of Warrants and the Company shall have received any
additional consideration which is payable upon such conversion, exchange or
exercise, the Preferred Stock will be validly issued, fully paid and
non-assessable.

         5. When (i) the Registration Statement shall have become effective
under the Act, (ii) the Blue Sky or securities laws of certain states shall have
been complied with, and (iii) the Common Stock shall have been issued upon
conversion or exchange of Debt Securities or Preferred Stock which, by their
respective terms, are convertible into or exchangeable for shares of Common
Stock, and the Company shall have received any additional consideration which is
payable upon such conversion or exchange, the Common Stock shall be validly
issued, fully paid and non-assessable.

         6. When (i) the Registration Statement shall have become effective
under the Act, (ii) the Blue Sky or securities laws of certain states shall have
been complied with, and (iii) a warrant agreement or agreements shall have been
authorized, executed and delivered by the Company and a warrant agent, and (iv)
the Warrants shall have been duly executed and delivered against payment
therefor, the Warrants shall be legally issued.

         I hereby consent to the filing of this opinion as an exhibit to the
Registration Statement. I also consent to the use of my name under the caption
"Legal Opinions" in the Prospectus contained in the Registration Statement.



                                            Very truly yours,

                                            /s/ Richard J. Ressler


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