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

    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2003-07-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001224501</rptOwnerCik>
            <rptOwnerName>GERRY ELBRIDGE T JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeSecurity>
        <securityTitle>
            <value>Phantom Stock</value>
                <footnoteId id="F1"/>
        </securityTitle>
        <conversionOrExercisePrice>
            <value>0</value>
        </conversionOrExercisePrice>
        <transactionDate>
            <value>2003-07-01</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>A</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>226</value>
            </transactionShares>
            <transactionValue>
                <value>0</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <exerciseDate>
            <value>1988-08-08</value>
                <footnoteId id="F2"/>
        </exerciseDate>
        <expirationDate>
            <value>1988-08-08</value>
        </expirationDate>
        <underlyingSecurity>
            <underlyingSecurityTitle>
                <value>Common Stock</value>
            </underlyingSecurityTitle>
            <underlyingSecurityShares>
                <value>226</value>
            </underlyingSecurityShares>
        </underlyingSecurity>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>7948</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </derivativeSecurity>

    <footnotes>
        <footnote id="F1">Distribution ratio for Phantom Stock Units is 1:1.  End of period holdings include Phantom Stock Units granted prior to 8/15/96 which are exempt from Section 16 reporting.      </footnote>
        <footnote id="F2">Phantom Stock Units are payable in cash only commencing at retirement.  (This footnote applies to both dates in Column 6 of Table II, &quot;Date Exercisable&quot; and &quot;Expiration Date&quot;.)</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: Carl W. von Bernuth, Attorney-in-Fact  For: Elbridge T. Gerry, Jr.</signatureName>
        <signatureDate>2003-07-03</signatureDate>
    </ownerSignature>

</ownershipDocument>
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X0101
4
2003-07-01
0
0000100885
UNION PACIFIC CORP
UNP
0001224501
GERRY ELBRIDGE T JR
1
0
0
0
Phantom Stock
0
2003-07-01
4
A
0
226
0
A
1988-08-08
1988-08-08
Common Stock
226
7948
D
Distribution ratio for Phantom Stock Units is 1:1.  End of period holdings include Phantom Stock Units granted prior to 8/15/96 which are exempt from Section 16 reporting.
Phantom Stock Units are payable in cash only commencing at retirement.  (This footnote applies to both dates in Column 6 of Table II, "Date Exercisable" and "Expiration Date".)
By: Carl W. von Bernuth, Attorney-in-Fact  For: Elbridge T. Gerry, Jr.
2003-07-03