TIL in 1964, riots broke out in North Philadelphia over a false rumor that police beat a pregnant black woman to death. Over 200 businesses were looted or destroyed. Most of those businesses never returned, which lead to much of North Philadelphia turning into the crime-ridden slum we see today.

http://www.philly.com/philly/blogs/TODAY-IN-PHILADELPHIA-HISTORY/The-Philadelphia-race-riot-of-August-1964.html