Dorothy Flood has fond memories of riding trains to visit family every summer as a child, but there was always a strange moment, a moment that has gnawed at her for decades. As Flood told NPR recently, "When we'd get to Baltimore, that was the Mason-Dixon Line...The African-Americans would go in the back ... and white people would go into separate cars...It didn't make any sense because I was going to school with them. I lived next to them. But now that I crossed that Mason-Dixon Line, I couldn't be with them? I didn't understand it." Flood and her grandmother never got to eat in the fancy dining car, instead eating homemade meals from shoeboxes. In an especially affecting anecdote, Flood remembers standing on one side of the dining car's etched glass door and tracing the fingertips of a girl her age on the other side of the door -- a white girl eating in the dining car.