Gerrymandering and Polarization

Tom Friedman becomes the latest in a very long string of pundits to blame congressional polarization on partisan gerrymandering of House districts. As Joshua Tucker points out no matter how many times people say this, there’s still no evidence that it’s true. You can see this pretty quickly if you consider that the Senate features perfect partisan sorting — Olympia Snowe is more conservative than all the Democrats and Ben Nelson is more liberal than all the Republicans. Senators are responsive to public opinion to some extent — Snowe is more liberal than other Republicans and Nelson more conservative than other Democrats — but only to a limited extent. You have lots of examples of two different senators representing the exact same state, and they amass very different voting records.

More rigorously, Nolan McCarty, Keith Poole and Howard Rosenthal have a paper called “Does Gerrymandering Cause Polarization?” The answer is no:

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.

Note also that historically polarization has been the rule in American politics. The times we live in are typical, not exceptional. It just happens to be the case that a lot of people alive today were acculturated to the unusual non-polarized politics of the 1930s-1970s in which the salience of racial issues scrambled partisan/ideological configurations. I think polarization is a good thing but even if you disagree the only proven way to minimize it is to have a large and influential white supremacist movement obtain substantial congressional representation.