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Gelman challenges what is increasingly the cliched way of viewing American politics--latte drinking, relatively well off Democrats vs. Wal-Mart, religious, working class Republicans. He instead offers clear data that demonstrates that most people on the poorer end of the political spectrum vote for Democrats, while most wealthier people vote Republican. So why the pattern of wealthier blue states and poorer red states? In blue states, a substantial portion of wealthier people vote Democratic, while in red states, most wealthier people stick with the Republicans. Thus in blue states, income doesn't predict all that well who you are going to vote for, while in Red states it does. My first intuition, when faced with this pattern, was to presume that it could be explained in good part by race, i.e. poorer people in red states like Mississippi are often African Americans, who vote heavily Democratic. But Gelman presents evidence that this is not the entire explanation. Notwithstanding everything you may have heard, poorer whites in these states tend to vote Democratic as well (albeit not in as high numbers as African Americans). The culture/taste wars between abortion rights, gay marriage, NPR vs. megachurches and Fox news is mainly being played out among the middle class and wealthy, who are sorting themselves into red and blue counties, and Republicans and Democrats, labels which are more meaningful than they used to be regarding ones social/cultural vision for the country. This is extremely interesting and useful to know, but beyond this point (restated and turned around many times), the book does not have much depth. There is virtually no ethnographic detail, only conclusions drawn from polls (and even those aren't all that fine-grained). To his credit, Gelman examines voting patterns in Mexico as well (American social scientists, and journalists are notorious for analysing the US in a vacuum). But this chapter fails to make much of an impact. Mexico votes in a perhaps less unexpected manner--the wealthier north goes conservative, while the poorer states of the south vote for the left party; but this probably has much to do with the more substantial economic policy differences between the parties in Mexico compared to the US. There is no detailed analysis of the political evolution of particular states in the US. He also tends to leave things at wealthier and poorer voters, without looking at more specific income groups or professions, or considering factors like union membership. If you are skeptical about this analysis, or wish to be clear on how Gelman arrived at his conclusions, by all means read the book. Otherwise you can probably glean enough of the analysis from this and other customer reviews.