re: Why do Northerners vote so differently in state races vs. presidential races?

I think the Midwest (OH, MI, WI, MO, Iowa, and maybe - just maybe - Illinois) will actually be trending back a bit purpleish-red over the next generation. I live in Illinois and some of the political self-loathing you hear around here is almost funny; people are so sick of what the local status quo here that a change - any change in any direction - is wanted. The unions have been dying a slow death, but it's getting ever closer, and the demographics set up well for the GOP around here.

I think you'll see it somewhat offset by VA, NC, and FL going more purpleish-blue and GA and maybe even Texas going purpleish.

Interestingly, Illinois lost almost 100,000 African-Americans between the 2000 and 2010 censuses. The century-long strangehold that the Democratic party on ethnic blocs (Irish, Polish, Italian, African-American, Hispanic, etc) in Chicago and the resulting massive influence the party had statewide because of this is starting to break, I think.