Illinois is pretty much Chicago (liberal and a majority of population) vs the rest of the state.
Other than its NW corner (minorities and unions), Indiana generally gets more conservative, whiter (and more racist) every mile you go south.
Iowa is pretty much red throughout - w/ the possible exception of modest sized college towns.
My impression is that states like Wisconsin, Michigan, Ohio are varying shades of purple, tending more blue in large cities, and more red the further away you get.
Head SW, into Missouri, Arkansas, Kansas, Nebraska, and you (generally) get fewer large cities, and more conservative populations.
So you can talk about Illinois politics, but you ought to acknowledge that those politics are VASTLY different in the northern 90 miles, than in the 300 miles south of that. I grew up in Chicago - where EVERYONE was Democrat and Catholic. It was quite the culture shock to attend the U of Illinois 140 miles to the south, where everyone (other than students/faculty) was Republican and protestant. Only gets mores as you head south.
This past weekend my future SIL was in town. He grew up in New Hampshire. To hear him talk, the northern 3/4 of NH is basically Dixie.
I bet a list of truly homogenous states would be rather short.