Politics as an Identity group

I scanned websites to see what young republicans, democrats and independents are talking about. Here's a quick list of links:

http://www.youngrepublicans.com/
http://www.yrnf.com/
http://theindependentvoter.com/
http://www.yda.org/

Political affiliations are an identity group in America. People make choices on what newspaper they read, what news channel they watch, and what issue is of importance based on political group they align with. It is interesting to see the differences between the above mentioned sites. The political groups set their own agenda, and their attention is placed in different issues. When I think of politics, I often associate a person's politics with class, but this is my own stereotype. American politics is so diverse.
There was recently a news piece on Good Morning America about politics and brand choice. Researchers could predict, based on your politics, what car you would likely drive, what newspapers, magazines and movies you prefer, and other consumer behavior. For example, if you drive a Volvo, you are most likely a Democrat.
Anyway, political affiliations are an identity group, and market researchers and advertisers know this about us. This is why Volvo runs ads in the New York Times.