Don't Blame Gerrymandering

This weekend, CNN aired an investigative report on partisan gerrymandering. The idea was to expose the practice as corrosive to democracy: “We wanted to show the most important part of the political process when it comes to congressional elections,” says Drew Griffin, who pursued the subject for CNN, “where politicians have been able to carve up the electoral process, therefore guaranteeing Democratic or Republican seats until they do this in the next ten years.” By Griffin’s lights, partisan gerrymandering is a practice that inflates the incumbency rate and leads to polarization and gridlock.

Courtesy of CNN

CNN investigative correspondent Drew Griffin with Representative Luis Gutierrez (D) Illinois

The problem with this analysis is that it doesn’t fit with the existing data. Yes, redistricting technology (politicians now have map-drawing software available to them) has become more sophisticated, and yes, this has coincided with a higher rate of incumbency. But that’s an accident of time. Given the extent to which the incumbency advantage for U.S. senators and state governors—non-gerrymandered offices—has grown with the incumbency rate for U.S. representatives, odds are good that there’s something else at work.

As it happens, there are reams of political-science research showing that partisan gerrymandering is low on the list of factors that explain the rising incumbency rate. That most representatives stand a good chance of re-election has more to do with things like the quality of challengers and the ability to raise funds than it does with partisan gerrymandering. Insofar that gerrymandering has an effect on competitiveness, it’s actually a good one; the upside of packing the bulk of a states’ Democrats into a few districts is that Republicans have a wider playing field. The downside is that this playing field goes both ways—if you break a single strong Republican district into several ones with a moderate GOP advantage, then you’ve increased the odds that a Democrat might win one of them.

Likewise, there isn’t much evidence for the claim that partisan gerrymandering is responsible for heightened polarization. In addition to showing the non-relationship between partisan sorting (the overwhelming presence of Democrats or Republicans in one district) and census-triggered redistricting, political scientists Nolan McCarty, Keith Poole, and Howard Rosenthal found that the increase in polarization “is mainly the consequence of the different ways Democrats and Republicans would represent the same districts.” In other words, given a marginal district, a Republican compiles a far more conservative record than a Democrat would. The increase in polarization among lawmakers has more to do with changes in political parties, party leadership, and issue priorities than it does gerrymandering.

Of course, partisan gerrymandering offers an easy explanation for the problems facing Congress, which is why I expect it to endure as an explanation for all that ails us, despite all available evidence.