This site demonstrates a point that I was talking about the other day. There is a lot fewer people in the "Bread Basket" then there are along the coasts (Including the Gulf of Mexico). I was relating the age of the civilization in the area of the country to it's tolerance for cultures and it's diversity. Notice I said relating, not correlating. I don't have any data for this theory yet, just some poor observations.
Election results by county.
Election results by country as an area cartogram based off of population of counties.
Cartograms are wonderfully powerful at conveying data (maybe not as wonderful at representing data). You should take a look at a few samples of them before you move on.