Ezra Klein has a new book out on our polarized nation. Bob Somerby sees polarization as the biggest issue we have. There's different views on causes, but it seems true that some of the polarization is rural versus urban.
I've a speculation to offer: Is it true that rural residents are less mobile than suburban and urban ones? My mental image is of counties which were settled in the 19th century, like Perry County, IL where my great grandparents settled. Since the initial settling, sons and daughters have moved away, leaving a relatively static population of the oldest son (who got the farm) and his wife. His children would repeat the cycle. All that should mean that current rural dwellers have a long family history with the area which would contrast to the mobility seen in urban and suburban areas.
I don't know whether that image is true. It might not be.