Chicago is the birthplace of gospel music, but when Lee Johnson opened New Sound Gospel 20 years ago, few people were selling it. That has all changed, thanks to the recent resurgence in gospel led by Kirk Franklin, whose platinum albums have crossed over into mainstream success. All the major labels now have gospel music divisions, and the rising tide has helped store owners like Johnson, who has since opened a second location at 10723 S. Halsted St. (tel. 773/785-8001). Both brim with records, CDs, and tapes, from gospel's greatest legend, Mahalia Jackson, to groups with names such as Gospel Gangstaz.