I live on the edge of the divide, and there are differences, but everyone farther out from the city than me still sees the Avengers just like everyone in the city does. The rednecks driving jacked up trucks are just as likely to listen to rap as they are to country. If you stop at a red light in the city on a nice day, you're still likely to hear someone singing about pickup trucks and beer from the car next to you. And 95+% of Americans bought something from Walmart last year.

I remember visiting relatives on the other side of the country in Burbank as a kid, and if anything the culture is far more homogeneous than it was then.