I just got off the phone with the Super 8 in Hagerstown (on U.S. 40, aka Dual Highway, same road as the track, about 5-6 miles or so west on 40). Rooms are $59.99 plus tax for Friday and Saturday night. But, if you mention the Mason-Dixon Race, the rate is $54.99 plus tax for those nights, so be sure to mention the Mason-Dixon Race for that lowered rate.
Phone number is (301) 739-5800 for the Super 8.