Steven Pinker, Professor of Psychology at Harvard, had a piece in the NY Times today entitled "Why Are States So Red and Blue?," in which he proposed that the tendencies of states to vote for Democrats or Republicans have deep roots in history: "The North and coasts are extensions of Europe and continued the government-driven civilizing process that had been gathering momentum since the Middle Ages. The South and West preserved the culture of honor that emerged in the anarchic territories of the growing country, tempered by their own civilizing forces of churches, families and temperance."
Pinker makes some interesting points, but overlooks one basic one: the identity of "red" and "blue" states has changed over time. In fact, the correlation between Democratic share of the vote in the 1936 and 2008 presidential elections is -.46: by and large, the states where the Democrats did best 1936 are the ones where they did worst in 2008. Of course, this is misleading, because the South has shifted from Democratic to Republican, while remaining conservative. But if we exclude the south, there is still a negative correlation (-.31). The relationship is shown in the figure below: the black dots are Southern states and the red dots are all other states. There are several outliers even when you exclude the South--the two states in the upper left are Vermont and Maine, which were strongly Republican in the 1930s. The four in the lower middle are Wyoming, Utah, Oklahoma, and Idaho, which were strongly Democratic in the 1930s. If you exclude those cases, the correlation is still about zero. Of course, the parties have changed too, but by today's standards, Roosevelt (D) was definitely the more liberal candidate in 1936. So either the civilizing process was very slow in gathering momentum or we need another hypothesis.