One of the reasons I came to Chicago was for the music. Not just to live in a city where significant national acts came through on a weekly basis, but one where music was part of the economic and social life of the city, a vast change from what I was used to. The city I grew up near, despite being just under 100,000 people, couldn't support an independent music store, much less bands—though one time, in college, a Roanoke band was the opening act on a three-act bill at the Empty Bottle. That was pretty exciting. (Though they didn't get much farther until they moved to Athens and hooked up with Elephant 6).
The other thing I perceived about the city from a distance was that the music scene was pretty evenly divided—Americana, weird hookless indie rock, odd avant-garde jazz as popular in Scandinavia as it is here (one semi-occasional sight when I worked at the Reader was European tourists having their photos taken outside the Jazz Mart). Diverse, with no one genre or culture remotely predominating.
So I was unsurprised to see the results of a survey that attempted to define the tastes of American music by state, The Geography of Music Preferences. Take the methodology as you will—an open Internet survey—but for Illinois, it seems to make a lot of sense. It's a northern state with a tremendous Southern influence; its rural bulk extends through culturally Midwestern (and quasi-Southern) regions but it's anchored by a huge urban center; and by the admittedly blunt criteria of the survey, it's basically a musical crossroads, or more accurately a mean. Of all the states in the Union, only Maine and New Hampshire seem to correlate as strongly with moderation in all things.
A good introduction to Illinois's musical folkways is the Illinois Humanities Council's Folksongs of Illinois series, which is as diverse—yet moderate!—as the survey says.