WALL, S.D. — Stacey Schulz parks in a rear lot to avoid the crowded Main Street entrances to her local pharmacy. “During the summer, it’s kind of hectic,” she said after greeting the pharmacist and technician by name. That’s because Schulz’s pharmacy is tucked inside Wall Drug, a tourist attraction that takes up almost an entire block and draws more than 2 million visitors a year to a community of fewer than 700 residents. The business is named after the town of Wall, which is just off Interstate 90 near Badlands National Park. Colorful, hand-painted billboards dot the roadside for hundreds of…