If you are thinking about moving to Minneapolis, it's a lovely city, but it's one of many Midwestern cities that is experiencing extreme gentrification, with much of the Cities more recent growths in liberal/leftist (leans far more liberal) political activism coming from a combination of older African-American and newer Somali-American communities, the music scene that grew up in the 80's, and always systemically ironic California expats who are the primary consumers of the gentrification model. Otherwise, apolitical chuddishness is kinda the normal unless you are way into the rural areas or upper bourgeois in the area.

Personally, if you are looking to be in that general area, I would suggest Madison or Milwaukee. While both have gentrification problems (particularly Milwaukee), they also have a far larger and more historic activist tradition that dates all the way back to the German settlers (which itself is problematic, I know). That being said, what that means is that co-op living is a far more common thing in those cities, which is traditionally how many of the political activist types I know meet for the first time. That being said, the activism cuts both ways, and out in Kenosha you will find the most virulent and nasty racist chuds or if you go down to Janesville or many other areas, libertarianism in all it's contradictions is the most dominant strain of political thought.

Or you could just try to go to Chicago and Detroit, but most of their activism is caught up in the Democratic party machine.