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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-12-01</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001544184</rptOwnerCik>
            <rptOwnerName>BUTLER ERIC L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1400 DOUGLAS STREET, STOP 1210</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>OMAHA</rptOwnerCity>
            <rptOwnerState>NE</rptOwnerState>
            <rptOwnerZipCode>68179</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <remarks>As previously announced by the issuer on a Form 8-K filed on October 25, 2017, effective December 1, 2017, Mr. Butler is no longer a Section 16 reporting officer of the issuer. As such, this voluntary Form 4 filing constitutes an exit filing for Mr. Butler.</remarks>

    <ownerSignature>
        <signatureName>By: Trevor L. Kingston, Attorney-in-Fact For: Eric L. Butler</signatureName>
        <signatureDate>2017-12-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2017-12-01
1
0000100885
UNION PACIFIC CORP
UNP
0001544184
BUTLER ERIC L
1400 DOUGLAS STREET, STOP 1210
OMAHA
NE
68179
0
1
0
0
Senior Vice President
As previously announced by the issuer on a Form 8-K filed on October 25, 2017, effective December 1, 2017, Mr. Butler is no longer a Section 16 reporting officer of the issuer. As such, this voluntary Form 4 filing constitutes an exit filing for Mr. Butler.
By: Trevor L. Kingston, Attorney-in-Fact For: Eric L. Butler
2017-12-01