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Zombie Politics: Redistricting and Party Polarization

- October 21, 2012

Aaron Blake:

The once-in-a-decade redistricting process has taken the nation’s already-polarized congressional map and — you guessed it! — made it even more polarized, says a new study from the nonpartisan election reform group Fair Vote

…The result is that the blue districts will, almost without fail, elect liberal Democrats, while the red districts will, almost without fail, elect conservative Republicans. And because these members basically need to please only one side of the aisle to win reelection, their incentive is to toe the party line just about 100 percent of the time.

Does redistricting makes the parties in Congress more polarized?   No.  If you want the simplest evidence, consider that polarization in the never-redistricted Senate mirrors that in the House.  If you want more sophisticated evidence, here, via Josh’s earlier post, are political scientists Nolan McCarty, Keith Poole and Howard Rosenthal (gated, earlier ungated version):


Both pundits and scholars have blamed increasing levels of partisan conflict and polarization in Congress on the effects of partisan gerrymandering. We assess whether there is a strong causal relationship between congressional districting and polarization. We find very little evidence for such a link. First, we show that congressional polarization is primarily a function of the differences in how Democrats and Republicans represent the same districts rather than a function of which districts each party represents or the distribution of constituency preferences. Second, we conduct simulations to gauge the level of polarization under various “neutral” districting procedures. We find that the actual levels of polarization are not much higher than those produced by the simulations. We do find that gerrymandering has increased the Republican seat share in the House; however, this increase is not an important source of polarization.

Die, zombie, die!

(Earlier posts in this series are here.)