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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-01-20</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000732417</issuerCik>
        <issuerName>HILLS BANCORPORATION</issuerName>
        <issuerTradingSymbol>HBIA.PK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001515018</rptOwnerCik>
            <rptOwnerName>MAIERS MARTY J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HILLS BANCORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>131 MAIN STREET</rptOwnerStreet2>
            <rptOwnerCity>HILLS</rptOwnerCity>
            <rptOwnerState>IA</rptOwnerState>
            <rptOwnerZipCode>52235</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP Director of Retail</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Marty J. Maiers by Shari DeMaris</signatureName>
        <signatureDate>2017-01-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2017-01-20
1
0000732417
HILLS BANCORPORATION
HBIA.PK
0001515018
MAIERS MARTY J
C/O HILLS BANCORPORATION
131 MAIN STREET
HILLS
IA
52235
0
1
0
0
SVP Director of Retail
/s/ Marty J. Maiers by Shari DeMaris
2017-01-20