Illinois- as a state, in general- has the largest Muslim population in the US per capita. (Not in raw numbers, but as a percentage of the state's population). Of course this is not happening everywhere in Illinois, which has some incredible urban density and suburbia and vast farmland that's near a whole lot of rivers. It's really just certain areas. May I point you to a specific part of Bridgeview, one of the suburbs of Chicago. Here's an article, a particular area near 87th Street and Harlem Avenue is known as Little Palestine.
http://chicagoreporter.com/they-call-it-little-palestine/
If you do happen to find your way to this Chicago suburb, I'd also like to make a plug for the Chicago Fire. They used to play at Soldier Field in the city right on the lake, but now their permanent home is at Toyota Park, a soccer specific stadium in Bridgeview. The team used to be really good but they've been one of the worst in the league for the past couple of years. Their season will be mercifully over this Sunday....but there are signs of improvement, we'll see how the new coach works out long term, and I will say this. In terms of fan experience, the Fire take care of you like no one else. In terms of fan experience, and especially if you have some sort of group event, the Chicago Fire at Toyota Park in Bridgeview are frequently rated as he best overall fan experience of Any North American sports franchise, and they're Always in the top two or three. This means the fan experience there is being compared to all sports teams across the MLS, MLB, NBA, NHL, NFL, and the CFL and Liga MX along with them, and the Chicago Fire are right at the top of this rather large list. They take very, very good care of their fans.
So if you're planning on doing anything in the US, keep an eye on this particular Chicago suburb. If you have some sort of group activity you want to do, the Chicago Fire will take great care of you any time between March and October, it's very reasonable in terms of price, and you've got Little Palestine right there in the neighborhood as well.