For Black women, education makes the least difference in earning potential, among other factors. Angie Stackhouse worked as a pharmacist, a loan officer, as a volunteer at homeless organizations and mostly as an electrician in Maryland, making $12.50 an hour. She's worked since she was 14. When the recession took her career seven years ago, she knew she'd find another one. Except, the only work available paid minimum wage. At 47-years-old, in 2010, Stackhouse enrolled in school to reinvent herself. "I'll definitely get a job," she recalls thinking, "because I'll have a degree." That was around the time President Obama...