Bryan Caplan, author of The Myth of the Rational Voter (formerly called The Logic of Collective Belief: The Political Economy of Voter Irrationality), wrote some nice things about our book and also posted a variant of this graph that I made by putting together a bunch of exit polls:

Bryan also comments that, to his eyes, the correlation between income and voting is pretty small. He writes, “As an economist, I [Caplan] was raised to expect virtually all poor people to be Democrats, and virtually all rich people to be Republicans. From this starting point, Gelman’s data show that income is practically irrelevant.” I agree that income matters less than one might think in the U.S., and it actually matters even less in most other countries for which we have data. As we discuss in the book, the correlation between income and economic ideology is low (and it varies quite a bit by state). On the other hand, it’s a difference of 20% between the high and low end, and that ain’t nothing. It’s the difference between voting like Massachusetts and voting like Texas. We’re always dancing around the magic 50% point, and so even small differences can be important. As Bryan says, a lot of how you interpret this depends on where you’re coming from.
I also agree with Bryan that we are not really shooting down the ideas of journalists and others, but rather looking at polls and elections in a different way. We did try to convey in the book that we respect the insights of the many journalists who’ve talked about the red-blue divide, and that we’re trying to go further by seeing how these divisions have changed over time and how they vary across different groups of the population.