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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-10-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001008544</rptOwnerCik>
            <rptOwnerName>MCCARTHY MICHAEL R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MCCARTHY GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1601 DODGE STREET, SUITE 3800</rptOwnerStreet2>
            <rptOwnerCity>OMAHA</rptOwnerCity>
            <rptOwnerState>NE</rptOwnerState>
            <rptOwnerZipCode>68102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2008-10-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This grant reflects the equitable adjustment of grants issued under the 2000 Directors Stock Plan to reflect the 2-for-1 stock split effected by Union Pacific Corporation in May 2008, in accordance with the terms of the plan.  We inadvertently issued only 1,000 shares of common stock to the recipient director upon his election instead of the 2,000 shares required by the plan.

On May 28, 2008, Union Pacific Corporation effected a 2-for-1 stock split in the form of a stock dividend.  Amounts of securities and the grant price or prices with respect to options, if any, and restricted stock or restricted stock units, if any, reported on this form have been adjusted to reflect the stock split.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: Trevor L. Kingston, Attorney-in-Fact  For: Michael R. McCarthy</signatureName>
        <signatureDate>2008-10-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0303
4
2008-10-24
0
0000100885
UNION PACIFIC CORP
UNP
0001008544
MCCARTHY MICHAEL R
C/O MCCARTHY GROUP, INC.
1601 DODGE STREET, SUITE 3800
OMAHA
NE
68102
1
0
0
0
Common Stock
2008-10-24
4
A
0
1000
0
A
2000
D
This grant reflects the equitable adjustment of grants issued under the 2000 Directors Stock Plan to reflect the 2-for-1 stock split effected by Union Pacific Corporation in May 2008, in accordance with the terms of the plan.  We inadvertently issued only 1,000 shares of common stock to the recipient director upon his election instead of the 2,000 shares required by the plan.

On May 28, 2008, Union Pacific Corporation effected a 2-for-1 stock split in the form of a stock dividend.  Amounts of securities and the grant price or prices with respect to options, if any, and restricted stock or restricted stock units, if any, reported on this form have been adjusted to reflect the stock split.
By: Trevor L. Kingston, Attorney-in-Fact  For: Michael R. McCarthy
2008-10-24