Why are race relations (between blacks and whites) in many Midwest cities so jagged?

I don't know about Cincinnati as I avoid going there as much as I can (not a city kinda person). But here in Hamilton it's not that bad. Neighborhoods that were once mostly whites or mostly blacks are starting to integrate fairly well. It's a huge change from when I was a teen in the 70's. There's a popular store near me, the owners are from the middle-east. We have a fair sized Hispanic population but they tend to stick to themselves.