<PAGE>

As filed with the Securities and Exchange Commission on July 1, 2003.

                                                   Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   ----------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

                                   ----------

                            UNION PACIFIC CORPORATION
             (Exact name of registrant as specified in its charter)

            UTAH                                         13-2626465
(State or other jurisdiction of             (I.R.S. Employer Identification No.)
incorporation or organization)

1416 DODGE STREET
OMAHA, NE                                                  68179
(Address of Principal Executive Offices)                 (Zip Code)

                       UNION PACIFIC FRUIT EXPRESS COMPANY
                AGREEMENT EMPLOYEE 401(K) RETIREMENT THRIFT PLAN
                              (Full title of plan)

                               CARL W. VON BERNUTH
                     SENIOR VICE PRESIDENT, GENERAL COUNSEL
                                  AND SECRETARY
                            UNION PACIFIC CORPORATION
                                1416 DODGE STREET
                                 OMAHA, NE 68179
                                 (402) 271-5777
 (Name, address and telephone number, including area code, of agent for service)

                         CALCULATION OF REGISTRATION FEE
<Table>
<Caption>
        TITLE OF SECURITIES                                        PROPOSED MAXIMUM            AMOUNT OF REGISTRATION
          TO BE REGISTERED       AMOUNT TO BE REGISTERED      AGGREGATE OFFERING PRICE(1)               FEE
      ----------------------     -----------------------      ---------------------------     ------------------------
<S>                              <C>                          <C>                             <C>
      Common Stock, Par
      Value $2.50 Per Share            $1,000,000                   $1,000,000.00                     $80.90

      Plan Interests                      (2)                            (2)                            (2)
</Table>

(1) Calculated in accordance with Rule 457(o) of the Securities Act of 1933.

(2) In addition, pursuant to Rule 416(c) under the Securities Act of 1933, this
Registration Statement also covers an indeterminate amount of interests to be
offered or sold pursuant to the Union Pacific Fruit Express Company Agreement
Employee 401(K) Retirement Thrift Plan. These securities have no offering price
and therefore, pursuant to Rule 457(h)(2), no separate registration fee is
required.



<PAGE>



                                     PART I
              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1. Plan Information.*


Item 2. Registrant Information and Employee Plan Annual Information.*

         *Information required by Part I of Form S-8 to be contained in the
Section 10(a) prospectus is omitted from this Registration Statement in
accordance with Rule 428 under the Securities Act of 1933, as amended (the
"Securities Act"), and the Note to Part I of Form S-8. The document(s)
containing such information will be sent or given to participating employees as
specified in Rule 428(b)(1) of the Securities Act. These documents and the
documents incorporated by reference into this Registration Statement pursuant to
Item 3 of Part II of this Registration Statement, taken together, constitute a
prospectus that meets the requirements of Section 10(a) of the Securities Act.

                                     PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

         The following documents, which have been filed previously by the Union
Pacific Corporation ("the Company") with the Securities and Exchange Commission
(the "Commission"), are incorporated by reference in this Registration Statement
and made a part hereof:

         (a)      The Company's Annual Report on Form 10-K for the fiscal year
                  ended December 31, 2002;

         (b)      All other reports filed pursuant to Section 13(a) or 15(d) of
                  the Securities Exchange Act of 1934, as amended (the "Exchange
                  Act") since the end of the fiscal year covered by the Annual
                  Report referred to in (a) above;

         (c)      The description of the Common Stock, par value $2.50 per
                  share, that is contained in the Company's Registration
                  Statement filed under the Exchange Act under File No. 1-6075,
                  including all amendments or reports filed for the purpose of
                  updating such description; and

         (d)      The Plan's Annual Report on Form 11-K for the fiscal year
                  ended December 31, 2002.

         All reports and other documents subsequently filed by the Company
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the
filing of a post-effective amendment which indicates that all securities offered
hereby have been sold or which deregisters all securities then remaining unsold,
shall be deemed to be incorporated by reference herein and to be part hereof
from the date of filing of such documents.

         For purposes of this Registration Statement, any statement contained in
a document incorporated or deemed to be incorporated by reference shall be
deemed to be modified or superseded to the extent that a statement contained
herein or in any other subsequently filed document which also is or is deemed to
be incorporated herein by reference modifies or supersedes such statement in
such document. Any statement so



                                      -2-


<PAGE>

modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Registration Statement.

Item 4. Description of Securities.

         Not applicable.

Item 5. Interests of Named Experts and Counsel.

         Not applicable.

Item 6. Indemnification of Directors and Officers.

         The Company is a Utah corporation. Section 16-10a-901 et seq. of the
Revised Business Corporation Act of Utah grants to a corporation the power and
in certain cases requires corporations to indemnify a person made a party to a
lawsuit or other proceeding because such person is or was a director or officer.
A corporation is further empowered to purchase insurance on behalf of any person
who is or was a director or officer against any liability asserted against him
or her and incurred by him or her in such capacity or arising out of his or her
status as such capacity. The Company's By-Laws provide for mandatory
indemnification of its directors, officers and employees in certain
circumstances. The Company maintains insurance on behalf of directors and
officers against liability asserted against them arising out of their status as
such.

         The Company's Articles of Incorporation eliminate in certain
circumstances the personal liability of directors of the Company for monetary
damages for a breach of their fiduciary duty as directors. This provision does
not eliminate the liability of a director for (i) the amount of a financial
benefit received by a director to which he or she is not entitled, (ii) an
intentional infliction of harm on the corporation or the shareholders, (iii) a
violation of Section 16-10a-842 of the Revised Business Corporation Act of Utah
(relating to the liability of directors for unlawful distributions) or (iv) an
intentional violation of criminal law.

Item 7. Exemption from Registration Claimed.

         Not applicable.

Item 8. Exhibits.

         The exhibits filed as part of this Registration Statement are as
follows:


  Exhibit Number                               Exhibit
  --------------                               -------

         23              -          Consent of Deloitte & Touche LLP

         24              -          Powers of Attorney



                                      -3-

<PAGE>

         The Registrant has submitted the Plan to the Internal Revenue Service
         (the "IRS") and received a determination letter dated April 24, 2003
         that the Plan is qualified under Section 401(a) of the Internal Revenue
         Code of 1986, as amended, conditioned on the adoption of certain
         amendments which will be made by the Registrant in a timely manner.

Item 9. Undertakings.

         (a) The undersigned Company hereby undertakes:

         (1) To file, during any period in which offers or sales are being made,
         a post-effective amendment to this Registration Statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
                  the Securities Act;

                  (ii) To reflect in the prospectus any facts or events arising
                  after the effective date of the Registration Statement (or the
                  most recent post-effective amendment thereof) which,
                  individually or in the aggregate, represent a fundamental
                  change in the information set forth in the Registration
                  Statement;

                  (iii) To include any material information with respect to the
                  plan of distribution not previously disclosed in the
                  Registration Statement or any material change to such
                  information in the Registration Statement;

         Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) of this
         Section do not apply if the information required to be included in a
         post-effective amendment by those paragraphs is contained in periodic
         reports filed with or furnished to the Commission by the Company
         pursuant to Section 13 or Section 15(d) of the Exchange Act that are
         incorporated by reference in the Registration Statement.

         (2) That, for the purpose of determining any liability under the
         Securities Act, each such post-effective amendment shall be deemed to
         be a new Registration Statement relating to the securities offered
         therein, and the offering of such securities at that time shall be
         deemed to be the initial bona fide offering thereof.

         (3) To remove from registration by means of a post-effective amendment
         any of the securities being registered which remain unsold at the
         termination of the offering.

         (b) The undersigned Company hereby undertakes that, for purposes of
         determining any liability under the Securities Act, each filing of the
         Company's Annual Report pursuant to Section 13(a) or Section 15(d) of
         the Exchange Act (and, where applicable, each filing of an employee
         benefit plan's annual report pursuant to Section 15(d) of the Exchange
         Act) that is incorporated by reference in the



                                      -4-

<PAGE>

         Registration Statement shall be deemed to be a new Registration
         Statement relating to the securities offered therein, and the offering
         of such securities at that time shall be deemed to be the initial bona
         fide offering thereof.

         (c) Insofar as indemnification for liabilities arising under the
         Securities Act may be permitted to directors, officers and controlling
         persons of the Company pursuant to the foregoing provisions, or
         otherwise, the Company has been advised that in the opinion of the
         Commission such indemnification is against public policy as expressed
         in the Securities Act and is, therefore, unenforceable. In the event
         that a claim for indemnification against such liabilities (other than
         payment by the Company of expenses incurred or paid by a director,
         officer or controlling person of the Company in the successful defense
         of any action, suit or proceeding) is asserted by such director,
         officer or controlling person in connection with the securities being
         registered, the Company will, unless in the opinion of its counsel the
         matter has been settled by controlling precedent, submit to a court of
         appropriate jurisdiction the question whether such indemnification by
         it is against public policy as expressed in the Securities Act and will
         be governed by the final adjudication of such issue.



                                      -5-

<PAGE>


                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the Company
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Omaha, State of Nebraska, on this 1st day of July,
2003.


                                          UNION PACIFIC CORPORATION


                                          By: /s/ Carl W. von Bernuth
                                              ---------------------------------
                                              Carl W. von Bernuth
                                              Senior Vice President,
                                              General Counsel and Secretary


         Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed below on this 1st day of July, 2003, by
the following persons in the capacities indicated.


<Table>
<Caption>
          Signature                                  Title
          ---------                                  -----
<S>                                    <C>
/s/ Richard K. Davidson                Chairman of the Board, President, Chief
-----------------------------          Executive Officer and Director
    (Richard K. Davidson)              (Principal Executive Officer)


/s/ James R. Young                     Executive Vice President - Finance
-----------------------------          (Principal Financial Officer)
    (James R. Young)


/s/ Richard J. Putz                    Vice President and Controller
-----------------------------          (Principal Accounting Officer)
    (Richard J. Putz)
</Table>



                                      -6-

<PAGE>


<Table>
<S>                                <C>             <C>
Philip F. Anschutz                 Director )
Thomas J. Donohue                  Director )      By: /s/ Carl W. von Bernuth
Archie W. Dunham                   Director )          ---------------------------------
Spencer F. Eccles                  Director )          (Carl W. von Bernuth
Ivor J. Evans                      Director )          ---------------------------------
Elbridge T. Gerry, Jr.             Director )          as Attorney-in-Fact)
Judith Richards Hope               Director )
Richard J. Mahoney                 Director )
Ernesto Zedillo Ponce de Leon      Director )
</Table>



                                      -7-


<PAGE>





                                INDEX TO EXHIBITS


<Table>
<Caption>
     Exhibit
     Number                                     Exhibit
     -------                                    -------
<S>                      <C>
       23                -          Consent of Deloitte & Touche LLP

       24                -          Powers of Attorney
</Table>
[{"type": "S-8", "sequence": "1", "filename": "d07132sv8.txt", "description": "FORM S-8", "secsgml_size_bytes": 15861}]
{"company-data": {"conformed-name": "UNION PACIFIC CORP", "cik": "0000100885", "assigned-sic": "4011", "irs-number": "132626465", "state-of-incorporation": "UT", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-106707", "film-number": "03768092"}, "business-address": {"street1": "1416 DODGE STREET", "street2": "ROOM 830", "city": "OMAHA", "state": "NE", "zip": "68179", "phone": "402 271 5213"}, "mail-address": {"street1": "1416 DODGE STREET", "street2": "ROOM 830", "city": "OMAHA", "state": "NE", "zip": "68179"}}
As filed with the Securities and Exchange Commission on July 1, 2003.

                                                   Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   ----------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

                                   ----------

                            UNION PACIFIC CORPORATION
             (Exact name of registrant as specified in its charter)

            UTAH                                         13-2626465
(State or other jurisdiction of             (I.R.S. Employer Identification No.)
incorporation or organization)

1416 DODGE STREET
OMAHA, NE                                                  68179
(Address of Principal Executive Offices)                 (Zip Code)

                       UNION PACIFIC FRUIT EXPRESS COMPANY
                AGREEMENT EMPLOYEE 401(K) RETIREMENT THRIFT PLAN
                              (Full title of plan)

                               CARL W. VON BERNUTH
                     SENIOR VICE PRESIDENT, GENERAL COUNSEL
                                  AND SECRETARY
                            UNION PACIFIC CORPORATION
                                1416 DODGE STREET
                                 OMAHA, NE 68179
                                 (402) 271-5777
 (Name, address and telephone number, including area code, of agent for service)

                         CALCULATION OF REGISTRATION FEE
TITLE OF SECURITIES                                        PROPOSED MAXIMUM            AMOUNT OF REGISTRATION
          TO BE REGISTERED       AMOUNT TO BE REGISTERED      AGGREGATE OFFERING PRICE(1)               FEE
      ----------------------     -----------------------      ---------------------------     ------------------------
Common Stock, Par
      Value $2.50 Per Share            $1,000,000                   $1,000,000.00                     $80.90

      Plan Interests                      (2)                            (2)                            (2)
(1) Calculated in accordance with Rule 457(o) of the Securities Act of 1933.

(2) In addition, pursuant to Rule 416(c) under the Securities Act of 1933, this
Registration Statement also covers an indeterminate amount of interests to be
offered or sold pursuant to the Union Pacific Fruit Express Company Agreement
Employee 401(K) Retirement Thrift Plan. These securities have no offering price
and therefore, pursuant to Rule 457(h)(2), no separate registration fee is
required.
PART I
              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1. Plan Information.*

Item 2. Registrant Information and Employee Plan Annual Information.*

         *Information required by Part I of Form S-8 to be contained in the
Section 10(a) prospectus is omitted from this Registration Statement in
accordance with Rule 428 under the Securities Act of 1933, as amended (the
"Securities Act"), and the Note to Part I of Form S-8. The document(s)
containing such information will be sent or given to participating employees as
specified in Rule 428(b)(1) of the Securities Act. These documents and the
documents incorporated by reference into this Registration Statement pursuant to
Item 3 of Part II of this Registration Statement, taken together, constitute a
prospectus that meets the requirements of Section 10(a) of the Securities Act.

                                     PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

         The following documents, which have been filed previously by the Union
Pacific Corporation ("the Company") with the Securities and Exchange Commission
(the "Commission"), are incorporated by reference in this Registration Statement
and made a part hereof:

         (a)      The Company's Annual Report on Form 10-K for the fiscal year
                  ended December 31, 2002;

         (b)      All other reports filed pursuant to Section 13(a) or 15(d) of
                  the Securities Exchange Act of 1934, as amended (the "Exchange
                  Act") since the end of the fiscal year covered by the Annual
                  Report referred to in (a) above;

         (c)      The description of the Common Stock, par value $2.50 per
                  share, that is contained in the Company's Registration
                  Statement filed under the Exchange Act under File No. 1-6075,
                  including all amendments or reports filed for the purpose of
                  updating such description; and

         (d)      The Plan's Annual Report on Form 11-K for the fiscal year
                  ended December 31, 2002.

         All reports and other documents subsequently filed by the Company
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the
filing of a post-effective amendment which indicates that all securities offered
hereby have been sold or which deregisters all securities then remaining unsold,
shall be deemed to be incorporated by reference herein and to be part hereof
from the date of filing of such documents.

         For purposes of this Registration Statement, any statement contained in
a document incorporated or deemed to be incorporated by reference shall be
deemed to be modified or superseded to the extent that a statement contained
herein or in any other subsequently filed document which also is or is deemed to
be incorporated herein by reference modifies or supersedes such statement in
such document. Any statement so

                                      -2-
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Registration Statement.

Item 4. Description of Securities.

         Not applicable.

Item 5. Interests of Named Experts and Counsel.

         Not applicable.

Item 6. Indemnification of Directors and Officers.

         The Company is a Utah corporation. Section 16-10a-901 et seq. of the
Revised Business Corporation Act of Utah grants to a corporation the power and
in certain cases requires corporations to indemnify a person made a party to a
lawsuit or other proceeding because such person is or was a director or officer.
A corporation is further empowered to purchase insurance on behalf of any person
who is or was a director or officer against any liability asserted against him
or her and incurred by him or her in such capacity or arising out of his or her
status as such capacity. The Company's By-Laws provide for mandatory
indemnification of its directors, officers and employees in certain
circumstances. The Company maintains insurance on behalf of directors and
officers against liability asserted against them arising out of their status as
such.

         The Company's Articles of Incorporation eliminate in certain
circumstances the personal liability of directors of the Company for monetary
damages for a breach of their fiduciary duty as directors. This provision does
not eliminate the liability of a director for (i) the amount of a financial
benefit received by a director to which he or she is not entitled, (ii) an
intentional infliction of harm on the corporation or the shareholders, (iii) a
violation of Section 16-10a-842 of the Revised Business Corporation Act of Utah
(relating to the liability of directors for unlawful distributions) or (iv) an
intentional violation of criminal law.

Item 7. Exemption from Registration Claimed.

         Not applicable.

Item 8. Exhibits.

         The exhibits filed as part of this Registration Statement are as
follows:

  Exhibit Number                               Exhibit
  --------------                               -------

         23              -          Consent of Deloitte & Touche LLP

         24              -          Powers of Attorney

                                      -3-
The Registrant has submitted the Plan to the Internal Revenue Service
         (the "IRS") and received a determination letter dated April 24, 2003
         that the Plan is qualified under Section 401(a) of the Internal Revenue
         Code of 1986, as amended, conditioned on the adoption of certain
         amendments which will be made by the Registrant in a timely manner.

Item 9. Undertakings.

         (a) The undersigned Company hereby undertakes:

         (1) To file, during any period in which offers or sales are being made,
         a post-effective amendment to this Registration Statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
                  the Securities Act;

                  (ii) To reflect in the prospectus any facts or events arising
                  after the effective date of the Registration Statement (or the
                  most recent post-effective amendment thereof) which,
                  individually or in the aggregate, represent a fundamental
                  change in the information set forth in the Registration
                  Statement;

                  (iii) To include any material information with respect to the
                  plan of distribution not previously disclosed in the
                  Registration Statement or any material change to such
                  information in the Registration Statement;

         Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) of this
         Section do not apply if the information required to be included in a
         post-effective amendment by those paragraphs is contained in periodic
         reports filed with or furnished to the Commission by the Company
         pursuant to Section 13 or Section 15(d) of the Exchange Act that are
         incorporated by reference in the Registration Statement.

         (2) That, for the purpose of determining any liability under the
         Securities Act, each such post-effective amendment shall be deemed to
         be a new Registration Statement relating to the securities offered
         therein, and the offering of such securities at that time shall be
         deemed to be the initial bona fide offering thereof.

         (3) To remove from registration by means of a post-effective amendment
         any of the securities being registered which remain unsold at the
         termination of the offering.

         (b) The undersigned Company hereby undertakes that, for purposes of
         determining any liability under the Securities Act, each filing of the
         Company's Annual Report pursuant to Section 13(a) or Section 15(d) of
         the Exchange Act (and, where applicable, each filing of an employee
         benefit plan's annual report pursuant to Section 15(d) of the Exchange
         Act) that is incorporated by reference in the

                                      -4-
Registration Statement shall be deemed to be a new Registration
         Statement relating to the securities offered therein, and the offering
         of such securities at that time shall be deemed to be the initial bona
         fide offering thereof.

         (c) Insofar as indemnification for liabilities arising under the
         Securities Act may be permitted to directors, officers and controlling
         persons of the Company pursuant to the foregoing provisions, or
         otherwise, the Company has been advised that in the opinion of the
         Commission such indemnification is against public policy as expressed
         in the Securities Act and is, therefore, unenforceable. In the event
         that a claim for indemnification against such liabilities (other than
         payment by the Company of expenses incurred or paid by a director,
         officer or controlling person of the Company in the successful defense
         of any action, suit or proceeding) is asserted by such director,
         officer or controlling person in connection with the securities being
         registered, the Company will, unless in the opinion of its counsel the
         matter has been settled by controlling precedent, submit to a court of
         appropriate jurisdiction the question whether such indemnification by
         it is against public policy as expressed in the Securities Act and will
         be governed by the final adjudication of such issue.

                                      -5-
SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the Company
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Omaha, State of Nebraska, on this 1st day of July,
2003.

                                          UNION PACIFIC CORPORATION

                                          By: /s/ Carl W. von Bernuth
                                              ---------------------------------
                                              Carl W. von Bernuth
                                              Senior Vice President,
                                              General Counsel and Secretary

         Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed below on this 1st day of July, 2003, by
the following persons in the capacities indicated.
Signature                                  Title
          ---------                                  -----
/s/ Richard K. Davidson                Chairman of the Board, President, Chief
-----------------------------          Executive Officer and Director
    (Richard K. Davidson)              (Principal Executive Officer)

/s/ James R. Young                     Executive Vice President - Finance
-----------------------------          (Principal Financial Officer)
    (James R. Young)

/s/ Richard J. Putz                    Vice President and Controller
-----------------------------          (Principal Accounting Officer)
    (Richard J. Putz)
-6-
Philip F. Anschutz                 Director )
Thomas J. Donohue                  Director )      By: /s/ Carl W. von Bernuth
Archie W. Dunham                   Director )          ---------------------------------
Spencer F. Eccles                  Director )          (Carl W. von Bernuth
Ivor J. Evans                      Director )          ---------------------------------
Elbridge T. Gerry, Jr.             Director )          as Attorney-in-Fact)
Judith Richards Hope               Director )
Richard J. Mahoney                 Director )
Ernesto Zedillo Ponce de Leon      Director )
-7-
INDEX TO EXHIBITS
Exhibit
     Number                                     Exhibit
     -------                                    -------
23                -          Consent of Deloitte & Touche LLP

       24                -          Powers of Attorney