When I first got to Northwestern, I wondered why walking around on campus could be so frustrating. Even when sidewalks were relatively empty, I would often have to walk way around people to pass without bumping into them. At first, I chalked it up to the geographic diversity of the school; maybe the people that came to this school were used to different ways of moving through a public place. But after talking to my Black friends about my experience, they echoed it: people at this predominantly White school would not move out of our way on the sidewalk. This...