On a summer afternoon in Chicago, Margaret Garner, CEO of the Chicago construction firm Broadway Consolidated, took a ride to Chicago's poverty-stressed 37th Ward. Dressed immaculately in a multicolored blouse, black pants and red steel-toe work boots, she had an appointment with a field of dirt and dreams. Garner surveyed the 11-acre site, where an old factory had recently been demolished, and proclaimed the future: "This will be Wal-Mart No. 5,402. But I can guarantee you, it won't be anything like Wal-Mart No. 5,401."
Garner is the first black woman ever hired by Wal-Mart to build a store. In the summer of...