Hi Lisa,
I think because of where you are located, Boxer Rebound in Northern IL is your best bet. You are in their service area (SE WI, N IL, NW IN). It would take you about 2 hours to get there, but they are wonderful people and do a really good job of placing the right boxer in your home. We went through them to get Precious a month ago and we could not be happier. Their website is boxerrebound.com. You can download and fill out an application, then mail it to them and they will contact you.
There is also a Boxer rescue located in the Indianapolis area. I believe it is called Central Indiana Boxer Rescue, but other than that I have no info on them. Try doing a search for them, or perhaps someone else familiar with them can give you more info.
Also go to americanboxerrescue.org. They can guide you towards approved rescues that serve your area, and you'll want to stick with rescues affiliated with them.
Good luck!
Jen