Chattanooga, TN, once one of the dirtiest industrial towns in the U.S., has evolved into an outdoor mecca, with American Way Magazine calling its Raccoon Mountain bike trail comparable to Moab.
Local SORBA chapter president, Trey Commander, says their initiative is to build 100 miles of trail by 2010, and the start of that is the 20-mile Raccoon Mountain trail loop around the mountain’s upper section.  It offers views of downtown Chattanooga and the Tennessee River Gorge.
SORBA has a great trails directory here with info about that and many other mountain bike trails throughout the Southeast.