I volunteer with Canter Chicago. We have some nice horses here (including a gorgeous 16.3 hand mare, a real stunner - she's dressage only but a lovely horse with a lovely temperament)The spring season at Hawthorne is ending tonight and all the Thoroughbreds are being moved to Arlington (or other tracks) and the Standardbreds will be doing harness racing at Hawthorne in the summer.
We just did a fund raiser with Galloping Out. They are very nice people. If you're uncomfortable getting a horse directly from the track, they bring them on to their farms, let them down a bit and train them. I think they have one farm down in St. Louis area but they are mostly northern Illinois.
If you have experience with OTTBs, I can vouch for both these groups. We really love seeing "our" horses go to good homes.