<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0101</schemaVersion>

<documentType>4</documentType>

    <periodOfReport>2003-05-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

<issuer>        <issuerCik>0000100885</issuerCik>
        <issuerName>UNION PACIFIC CORP</issuerName>
<issuerTradingSymbol>UNP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001200010</rptOwnerCik>
            <rptOwnerName>KORALESKI JOHN J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
<reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP MKTG &amp; SALES</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
            <footnoteId id="F1"/>
        </securityTitle>
        <transactionDate>
            <value>2003-05-07</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>M</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>5000</value>
            </transactionShares>
            <transactionValue>
                <value>42.87</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>127376</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
        </securityTitle>
        <transactionDate>
            <value>2003-05-07</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>F</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>3554</value>
            </transactionShares>
            <transactionValue>
                <value>60.31</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>D</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>123822</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
        </securityTitle>
        <transactionDate>
            <value>2003-05-07</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>F</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>710</value>
            </transactionShares>
            <transactionValue>
                <value>60.31</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>D</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>123112</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
            <footnoteId id="F2"/>
        </securityTitle>
        <transactionDate>
            <value>2003-05-07</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>J</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>4.5223</value>
            </transactionShares>
            <transactionValue>
                <value>0</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>1440.6923</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>I</value>
            </directOrIndirectOwnership>
            <natureOfOwnership>
                <value>by Managed Account</value>
            </natureOfOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
            <footnoteId id="F3"/>
        </securityTitle>
        <transactionDate>
            <value>2003-05-07</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>J</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>0</value>
            </transactionShares>
            <transactionValue>
                <value>0</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>4004</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>I</value>
            </directOrIndirectOwnership>
            <natureOfOwnership>
                <value>by Partnership</value>
            </natureOfOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <derivativeSecurity>
        <securityTitle>
            <value>Non-Qualified Stock Option (right to buy)</value>
                <footnoteId id="F1"/>
        </securityTitle>
        <conversionOrExercisePrice>
            <value>42.87</value>
        </conversionOrExercisePrice>
        <transactionDate>
            <value>2003-05-07</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>M</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>5000</value>
            </transactionShares>
            <transactionValue>
                <value>0</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>D</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <exerciseDate>
            <value>1994-11-18</value>
        </exerciseDate>
        <expirationDate>
            <value>2003-11-18</value>
        </expirationDate>
        <underlyingSecurity>
            <underlyingSecurityTitle>
                <value>Common Stock</value>
            </underlyingSecurityTitle>
            <underlyingSecurityShares>
                <value>5000</value>
            </underlyingSecurityShares>
        </underlyingSecurity>
        <postTransactionAmounts>
            <valueOwnedFollowingTransaction>
                <value>6059</value>
            </valueOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </derivativeSecurity>

    <footnotes>
        <footnote id="F1">Number of shares and option price of outstanding options adjusted 10/16/96 to reflect new values following the spin-off of Union Pacific Resources Group, Inc.      </footnote>
        <footnote id="F2">Includes holdings in Union Pacific's Payroll-based and Tax-reduction stock ownership plans and 401(k) plan as of Transaction Date.       </footnote>
        <footnote id="F3">Represents shares held in the Koraleski Family Limited Partnership (FLP), of which the reporting person and his wife are the sole general partners and the reporting person, his wife, and his children are the sole limited partners.  The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.   </footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: Carl W. von Bernuth, Attorney-in-Fact  For: John J. Koraleski</signatureName>
        <signatureDate>2003-05-08</signatureDate>
    </ownerSignature>

</ownershipDocument>
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X0101
4
2003-05-07
0
0000100885
UNION PACIFIC CORP
UNP
0001200010
KORALESKI JOHN J
0
1
0
0
EVP MKTG & SALES
Common Stock
2003-05-07
4
M
0
5000
42.87
A
127376
D
Common Stock
2003-05-07
4
F
0
3554
60.31
D
123822
D
Common Stock
2003-05-07
4
F
0
710
60.31
D
123112
D
Common Stock
2003-05-07
4
J
0
4.5223
0
A
1440.6923
I
by Managed Account
Common Stock
2003-05-07
4
J
0
0
0
A
4004
I
by Partnership
Non-Qualified Stock Option (right to buy)
42.87
2003-05-07
4
M
0
5000
0
D
1994-11-18
2003-11-18
Common Stock
5000
6059
D
Number of shares and option price of outstanding options adjusted 10/16/96 to reflect new values following the spin-off of Union Pacific Resources Group, Inc.
Includes holdings in Union Pacific's Payroll-based and Tax-reduction stock ownership plans and 401(k) plan as of Transaction Date.
Represents shares held in the Koraleski Family Limited Partnership (FLP), of which the reporting person and his wife are the sole general partners and the reporting person, his wife, and his children are the sole limited partners.  The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.
By: Carl W. von Bernuth, Attorney-in-Fact  For: John J. Koraleski
2003-05-08