"Why Are States So Red and Blue?"

I'm not sure what this theory says about Indiana, 2008 notwithstanding, although it's easy to explain New Albany as an extension of the antebellum South. Perhaps we have insufficient Great Lakes coastline.

Why Are States So Red and Blue?, by Steven Pinker (New York Times)

Regardless of who wins the presidential election, we already know now how most of the electoral map will be colored, which will be close to the way it has been colored for decades. Broadly speaking, the Southern and Western desert and mountain states will vote for the candidate who endorses an aggressive military, a role for religion in public life, laissez-faire economic policies, private ownership of guns and relaxed conditions for using them, less regulation and taxation, and a valorization of the traditional family.

Northeastern and most coastal states will vote for the candidate who is more closely aligned with international cooperation and engagement, secularism and science, gun control, individual freedom in culture and sexuality, and a greater role for the government in protecting the environment and ensuring economic equality.