Madam C. J. Walker—reputed to be America’s first self-made woman millionaire—has long been celebrated for her rags-to-riches story. Born to former slaves in the Louisiana Delta in the aftermath of the Civil War, married at fourteen, and widowed at twenty, Walker spent the first decades of her life as a laundress, laboring in conditions that paralleled the lives of countless poor and working-class African American women. By the time of her death in 1919, however, Walker had refashioned herself into one of the most famous African American figures in the nation: the owner and president of...