I would say
redlining, both historically and currently, plays a large part.
Like many things racial, though, it's a cycle. The residents of a predominantly black neighborhood are often at a socioeconomic disadvantage, so they are essentially stuck. When they send their children to school, they get a half-assed education because, despite the neighborhoods taxes being high in regards to the surrounding neighborhoods, it is still relatively little money, so the schools have under-trained teachers and a lack of resources. These kids get a high school education or less because of circumstances outside of their control, so they end up in dead end minimum wage jobs or doing crime. This either lands them in the same neighborhood they grew up in because they can't afford anything else, in prison or dead. Rinse and repeat.
Add
gentrification to the mix to explain why certain neighborhoods that used to be predominantly black are now mostly white or a part of the business district.