Density and Partisanship

The best thing about having a relatively high-traffic blog, is that I can just mention analysis I’d like to see and then more often than not someone smarter than me goes and does it. The other day, I was wondering what would happen if you analyzed county-level population density in terms of political behavior. And now Dave Shor’s gone and done the math. Here’s one chart:


That’s the result of “a regression on 948 counties in 10 states to model Kerry’s two-way share of the vote” and it’s not just a line on a page, it’s a statistically significant correlation. But it’s not a huge effect: “if a SimCity-like God multiplies a county’s population by 3, Kerry’s county-level share of the vote would increase by about six tenths of a point.” Then there’s this:


It turns out that “overall density isn’t really as important as relative density within the state” and so “by looking at a counties voting population as a fraction of the overall electorate of the state, we see that even after accounting for overall density, it’s better to be a democratic candidate in the densest city in Iowa then to in the second most dense city in New York.” Interesting, and not really what I expected.