redistricting and polarization

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    Redistricting and Polarization

    MicahAltmanandMichaelMcDonald*

    CorrectedManuscriptForthcomingin

    AmericanGridlock:TheSources,Character,andImpactofPoliticalPolarization,

    2015,JamesA.Thurber,AntoineYoshinaka(Eds),CambridgeUniversityPress.

    WereviewhowtheideologicalpolarizationofmembersoftheHouseof

    Representatives(elitepolarization)isaffectedby:

    sortingofpartiesincumbentsintomoreideologically

    compatibledistricts,

    replacementofincumbentsbymoreideologicallyextreme

    successors,

    *Authorsarelistedinalphabeticalorder.Wedescribecontributionstothe

    chapterusingastandardtaxonomy(Allenetal.2014).MicahAltmanandMichaelMcDonaldweretheleadauthors,takingequalresponsibilityforrevisions.MichaelMcDonaldauthoredthefirstdraftofthemanuscriptandwasprimarilyresponsibleforthestatisticalanalysis.Bothcontributedtotheconceptionofthereport(includingcoreideasandstatementofresearchquestions),tothemethodology,totheprojectadministration,tothedatacollection,andtothewritingthroughcriticalreviewandcommentary.

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    thedrawingofmoreideologicallyextremedistricts.

    Weshowtherearefewercompetitivecongressionaldistrictshavinga

    nearbalanceofDemocratsandRepublicansfollowingredistricting.

    Weshowthatmorecompetitivedistrictscanbedrawnwithout

    sacrificingothervalues,suchascompactnessorminorityrepresentation.

    Wediscusstheprospectsforredistrictingreform.

    IncreasingideologicalpolarizationofAmericanpoliticalelites(elitepolarization)

    hascoincidedwithamarkedincreaseofpolicygridlockwithinthenational

    government.Concernswiththegovernmentsabilitytoaddressmajorpolicyissues,

    eventhosewithbroadpublicsupport,haveledmanytosearchforcausesforand

    solutionstoagovernmentsoparalyzedthatitcannotsatisfythebasicdemocratic

    valueofexecutingthewillofitspeople.

    Amongthefrequentlycitedcausesforelitepolarizationisredistricting,the

    processofperiodicallydrawingdistrictboundariestoostensiblyalignthemwith

    communitiesofinterest,representationalcriteria,andneutraladministrativegoals,

    suchasequalizingpopulationsfollowinganewdecennialcensus.Statesare

    responsiblefordrawingHouseofRepresentativesdistrictboundarylines;inmost

    states,politiciansareinchargeoftheprocess,creatinganobviousconflictof

    interestbecauseredistrictingaffectstheirchancesofreelection.

    Redistrictingspotentialcontributionstoelitepolarizationemergefromthe

    motivesofindividualpoliticiansandpoliticalparties.Districtboundarylinesmaybe

    manipulatedtoaffectelectionoutcomesbyshoringupanotherwisecompetitive

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    district(adistrictwithanearbalanceofDemocraticandRepublicanvoters)by

    addingsupportersofthepartyonewishestoadvantageorsubtractingthe

    opposition.Inredistricting,thereareopportunitiesforbipartisanshipthatelude

    nationalpolicymaking:oneincumbentstrashisanotherstreasure,whereby

    incumbentsofdifferentpartiesswapconstituentsunfavorabletotheirparty,but

    supporttheother.Iflegislatorsreflectthewilloftheirconstituents,elite

    polarizationincreaseswhendistrictsaremademoreideologicallyhomogeneousas

    reelection-seekingincumbentshavelessreasontomoderatetheirpositionstowin

    overindependentsortheotherpartyssupporters.

    Reformershaveamendedtheredistrictingprocessinahandfulofstatesto

    imposelimitations,includingmostrecentlyinNewYorkthrougha2014

    constitutionalreferendumapprovedbyvoters.Amongthetechnicalinnovations

    thatquietlyemergedduringthelastroundofredistrictingispublicaccesstoweb-

    deployedredistrictingsoftwareanddata,whichenabledgreaterpublicparticipation

    inthedrawingofalternativeredistrictingplans(AltmanandMcDonald2014b).The

    publicapproachesredistrictinginafundamentallydifferentmannerthan

    politicians,particularlywithrespecttopoliticalgoalssuchaspartisanfairnessand

    districtcompetition(AltmanandMcDonald2013,2014a,2014c).Thesepublicplans

    therebyprovideabenchmarkcomparisontoplansfabricatedbypoliticiansto

    concretelyassesshowdistrictsmaybemademorecompetitivethroughreform

    effortsandtowhatdegreethismayamelioratepolarization.

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    The Causal Relationship between Redistricting and Polarization

    Figure 1 Causal Connections Affecting Elite Polarization

    Muchhasbeenwrittenaboutthecausesandconsequencesofpoliticalpolarization,

    includingbythecontributingauthorstothisvolume.Ourpurposeisnottorehash

    theextensivepolarizationliterature.However,wedowishtoprovidecontextfor

    redistrictingsrole.InFigure1wesketchhowredistrictingfitswithintheoretical

    frameworksexplainingelitepolarizationoftheHouseofRepresentatives.The

    linkagebetweenredistrictingandelitepolarizationismediatedthroughdistrict

    partisanship,asvisualizedinFigure1.Thecausalchainfromredistrictingtoelite

    polarizationhastwonecessaryconditions.First,theideologicalcharacterof

    districtsconstituenciesmustberelatedtotheideologicalcharacteroftheirelected

    representatives.Second,redistrictingmustbeabletoaffectdistrictsideologies.We

    beginourdiscussionofthefirstordercausalconnectionswithcausesthatdirectly

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    affectelitepolarization,andthenwithsecondordercausalconnectionsaffecting

    thesefirstordercausalconnections.

    First Order Connection: District Partisanship Elite Polarization

    Withrespecttothefirstcondition,therearenoreliablenationalsurveymeasures

    fortheideologyofdistrictsconstituenciessincesamplesizeswithindistrictsare

    typicallytoosmalltodevelopreliablemeasures.Scholarsfrequentlymeasure

    districtsideologiesusingdistrictspartisanship,constructedfromelectionresults

    forstatewideoffices(McDonald2014).Presidentialelectionresultsareanalyzedfor

    nationalstudiessincethisisthesoleofficeelectednationally,thusprovidinga

    comparablemetricacrossallcongressionaldistricts.Wefollowthescholarlynorm

    equatingdistrictideologywithdistrictpartisanship.

    Themedianvotertheoremprovidesatheoreticalbasistoexpectthatdistrict

    partisanshipisafactorinrepresentativesideologies.Downs(1957)formallyshows

    howinplurality-wintwo-candidateelections,candidateswhowishtowinoffice

    will,inequilibrium,positiontheirideologysuchthatitisthesameasthedistricts

    medianvotersideology,inanelectoratewhereallvotersaredistributedalonga

    one-dimensionalleft-rightideologicalcontinuum.(Thisis,ofcourse,acaricatureof

    Downssnuancedtheory;wediscusscomplicationsandothermotives

    subsequently.)

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    Thelogicissimpleand,intheabstract,plausible.Consideracandidatewhose

    primarymotivationistogetelected.Acandidatewinsofficebyreceiving50percent

    plusoneofthevotes.Ifvoterspreferthecandidatewiththeclosestideology,then

    withoutknowingwhattheothercandidatewilldo,thefirstcandidateisalwaysbest

    offpositioninghisorherideologyatthemedianvoter.Therearetwocasesto

    consider.Caseone:ifthesecondcandidatepositionsatanypointotherthanthe

    median,thefirstcandidateonthemedianissupportedbyallvoterstotheleftor

    right(thosewithanideologyintheoppositedirectionfromthemedianasthe

    secondcandidatesposition),aswellashalfofthevotersbetweenthemedianand

    theideologyofthesecondcandidate.Thefirstcandidatewinsandthesecondloses.

    Casetwo:ifthesecondcandidatealsopositionsatthemedianvoter,thenvotersare

    indifferentbetweenthetwocandidatesandtheyrandomlychoosebetweenthetwo

    candidates.Afirstcandidatewhochoosesapositionotherthanthemedianis

    gamblingthattheothercandidatewillpositionhis-orherselfevenfurtherfromthe

    median.Whytakethisriskwhenthereisaclearpathwaytovictorybypositioning

    atthemedian?

    Theredistrictingapplicationisstraightforward.Theideologyofthemedian

    voterofadistrictisrelatedtotheproportionofvotersontheleftandright(i.e.,

    DemocratsandRepublicans)whoareassignedtoadistrict.Ifmorevotersonthe

    leftorrightareaddedtoadistrict,theideologyofthemedianvoterofthedistrict

    willbeavoterfurthertotheleftorright,respectively.Thoseinchargeof

    redistrictingthushavetheabilitytoaffectnotonlywhichpartyisfavoredtowina

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    district,but,bymanipulatingtheproportionofvotersinadistrictontheleftor

    right,theideologicalcharacterofthewinningcandidateaswell.

    Toempiricallydemonstratetherelationshipbetweendistrictpartisanship

    andelitepolarization,whichwewillrefertoagainwhenwedescribeothercausal

    pathways,weplotameasureofdistrictpartisanshipagainstameasureofmembers

    ideologyinFigure2.OurmeasureofdistrictpartisanshipistheMcCainshareofthe

    ObamaandMcCain2008presidentialvote,orwhatiscommonlycalledthetwo-

    partyvote.AhigherpercentagethusdescribesamoreRepublicandistrict.Wemight

    reasonablyinferthatdistrictpartisanshipproxiesconstituentsideology,witha

    moreRepublicandistrictsignalingamoreconservativeconstituency.Ourmeasure

    ofmembersideologyisPooleandRosenthals(2000)firstDW-NOMINATE

    dimension,whichplacesmembersrollcallvotesonaleftrightcontinuum,with

    highervaluesrelatedtoamoreconservativerollcallvotehistory.NOMINATE

    scoresareendogenoustoCongress,meaningthattheyarebasedonobservableroll

    callvotesthataretheendproductofthelegislativeprocess,andmaynotbetrue

    measuresofmembersideology.Ifonecaresaboutelitepolarizationwithin

    Congress,theyserveasastaticsnapshotofthecurrentCongress.Wefurther

    identifyDemocratswithaDandRepublicanswithanR,anddrawasimplelinear

    regressionlineforeachpartisantype.

    TherearethreeimportantfeaturesofFigure2:(1)thecorrelationbetween

    districtpartisanshipandmembersideologies,(2)partydivergenceofmembers

    fromdifferentpartiesrepresentingdistrictswithsimilarpartisanship,and(3)

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    candidatedivergenceamongmembersofthesamepartyrepresentingdistri