This gives us a good idea about how counties with various population densities vote. Notice that the most populous counties vote Democrat. I was not able to find the date of this data, but Harris, Dallas and Bexar counties in Texas all went blue in 2012 - which fits the general mold.
I have past posts linking to stories pointing out that areas with high density - cities - tend to be more Democrat/liberal than suburban and rural areas. Perhaps communitarian and egalitarian values become important when people live on top of each other. Individualism matters more when one has lots of space surrounding them.
Its an idea.
