If you're including college football teams, I can say that the UW vs. WSU divide can definitely have some political overtones. Ask a diehard UW fan to describe a typical WSU supporter, and they'll give you a bunch of Republican/Tea Party stereotypes (country hick, uneducated, redneck). Ask as diehard WSU fan to describe a typical UW supporter, and you'll get a bunch of stereotypes of Democrats (elitist, snob, pothead, etc.)
Well the stereotypes aren't exactly wrong, from what I've seen. 
I'm pretty sure Oregon and Oregon State have a similar, but slightly less obvious divide too.
I can't say I disagree.
Oregon has the interesting added factor of having the support of the anarchist subculture in Eugene. It's kind of like the Oakland Raiders of the Pac-12.
