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

    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2003-06-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001200005</rptOwnerCik>
            <rptOwnerName>JONES MARY S</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>VP &amp; TREASURER UPC</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
            <footnoteId id="F1"/>
        </securityTitle>
        <transactionDate>
            <value>2003-06-04</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>M</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>1115</value>
            </transactionShares>
            <transactionValue>
                <value>42.87</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>28069</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
            <footnoteId id="F2"/>
        </securityTitle>
        <transactionDate>
            <value>2003-06-04</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>F</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>777</value>
            </transactionShares>
            <transactionValue>
                <value>61.45</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>D</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>27292</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <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">The reporting person also has the following indirect holding: 1) 713.7787 units by a Managed Account which include holdings in Union Pacific's Payroll Based and Tax Reduction Stock Ownership Plans and 401(k) Plan as of the Transaction Date.  (Due to system limitations, this footnote is shown in Column 1 versus Column 5 of Table 1 where it normally would appear.)</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: Carl W. von Bernuth, Attorney-in-Fact  For: Mary S. Jones</signatureName>
        <signatureDate>2003-06-04</signatureDate>
    </ownerSignature>

</ownershipDocument>
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X0101
4
2003-06-04
0
0000100885
UNION PACIFIC CORP
UNP
0001200005
JONES MARY S
0
1
0
0
VP & TREASURER UPC
Common Stock
2003-06-04
4
M
0
1115
42.87
A
28069
D
Common Stock
2003-06-04
4
F
0
777
61.45
D
27292
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.
The reporting person also has the following indirect holding: 1) 713.7787 units by a Managed Account which include holdings in Union Pacific's Payroll Based and Tax Reduction Stock Ownership Plans and 401(k) Plan as of the Transaction Date.  (Due to system limitations, this footnote is shown in Column 1 versus Column 5 of Table 1 where it normally would appear.)
By: Carl W. von Bernuth, Attorney-in-Fact  For: Mary S. Jones
2003-06-04