We used to make a trip to Northwest Missouri almost every spring to hunt them. That was 20 years ago, and at that time they didn't come east if the Mississippi in large numbers. About 5 years ago, we tried a place in Southern IL. The hunting was slow, but there were lots of birds. I have heard that some areas of Southwest IN are starting to get quite a few snows.
It's definitely a matter of timing. Ideally you want to hunt the juvenile birds, which are typically not the first ones to come north in the spring. If you decide to go, do some research into the local guides. There are some good ones, and a lot of hacks...