You might want to check out www.chaain.org.  This is the website for a loose "coalition" of local AD/HD support groups, both physical and virtual.  Somewhere on the site (I haven't looked at it in months!) there is info about other groups.

 

I can tell you for sure that there are groups that meet in Chicago, Park Ridge, Naperville and I believe Lincolnshire (although it may be another northern suburb)... and there might be others as well.