Santa Cruz County, California must be up there. The opening of UC Santa Cruz in the mid 60s has transformed this traditionally Republican coastal county into one of the most hard-left areas in the country (Angela Davis is a professor at UC Santa Cruz, 'nuff said).
No, a lot of the shift happened because the Republican party went crazy hard right. The university played a role but the trend is seen all over the bay area, and really accelerated with that dumbass Bush. Acting like some sort of uneducated redneck is not going to play well in that part of the country.
How much can Romney improve in the area? Obviously Obama still wins overwhelmingly.