The difference among these areas was race. In Detroit, "redlining" was a practice that efficiently barred specific groups—African-Americans, Eastern Europeans, Arabs—from access to mortgages and other financial resources. We can still see landmarks such as the Birwood Wall, a six-foot-high wall explicitly built to mark the boundary of white and black neighborhoods.
My goodness, I can hardly imagine that even in the internet access there's still a discrimination. What more in the real wolrd.