Quotes from Andrew Gelman

1. Voters in richer states support the Democrats even though within any given state, richer voters tend to support the Republicans. 2. The slope within a state—the pattern that richer voters support the Republicans—is strongest in poor, rural, Republican-leaning red states and weakest in rich, urban blue states. 3. The systematic differences between rich and poor states have largely arisen in the past twenty years.

As noted by Ronald Inglehart, director of the World Values Survey, people in richer countries tend to be less religious, but the United States is an exception, as a rich country with a high rate of religious observance and belief; see figure 6.1.

Part of the story is race. In poor southern states such as Mississippi, the rich-poor divide coincides with a racial divide, which, given the differences between the two parties on racial issues, will lead to a bigger difference between the voting patterns of rich and poor. Beyond this, race is tied into economic issues and policies: given the high correlation of income and race, redistribution often looks like a racial policy.

The paradox is that, while these rich states have become more strongly Democratic over time, rich voters have remained consistently more Republican than voters on the lower end of the income scale.

The current pattern—of religious attenders being more Republican, especially among high-income voters—has been happening since Bill Clinton's election in 1992, with no consistent patterns before then.

The rich Northeast and West of the United States, along with much of Europe, seem to have moved toward what might be called a postindustrial politics in which supporters of liberal and conservative parties differ more on religion than on income, and politics feels more like a culture war than a class war. Meanwhile, poorer states in the South and middle of the country look more like Mexico, with a more traditional pattern of votes of the rich and poor.

The concern—and it is a real one—is that ideology has become so strong that it is currently impossible for opposing sides to have a reasoned discussion or even agree on a common set of underlying facts about the world, leading ultimately to policies supported by 50%-plus-one of the voters and considered illegitimate by the other half.

The difference between "significant" and "not significant" is not itself statistically significant

Each political party has marginalized the political center, because they feel that all they have to do is energize their base. It's a political strategy. Before, you know, when I was in politics, it was a matter of both parties competing for the center, competing for the independents. That is gone now. —John Danforth, former U.S. senator from Missouri, 2006

As figure A.6 shows, state-by-state election swings have generally been declining over the past few decades. The red-blue map is much more stable from election to election than it used to be.

This is what graphics are all about: showing the details and the patterns all at once.

Individual income is a positive predictor and state average income is a negative predictor of Republican voting.

Rich voters are much more Republican than poor voters, especially in poor states, a pattern that emerged after 1990.

In asking why the patterns within states differ from those among states, we are specifically interested in why rich and poor have diverged so much in poor states and so little in rich states.

Social networks are indeed politically segregated—surveys find Democrats are more likely to know more Democrats and Republicans more likely to know more Republicans—but it is difficult to know how much is from geography (red or blue states, regions, neighborhoods, and workplaces) and the extent to which polarized social networks cause, or are the product of, polarization in attitudes.

As figure 5.1 shows, in the past the United States was not more economically stratified than other countries, but the last thirty years have seen exceptional growth in the incomes of the richest Americans.

The poor have been getting richer faster in the poor states and the rich have been getting richer faster in the rich states; see figure 5.3.

Income inequality has been increasing in Democratic-leaning states and decreasing in Republican-leaning states. Tax cuts and deregulation (which have been championed by Republicans and reluctantly accepted by Democrats) have increased inequality in the richest states, while poverty-relief programs (largely instituted in Democratic administrations but generally left standing by Republicans) have decreased inequality in poor states.