Most blacks who migrated to cities from the south after the war were met with at the very least skepticism, though usually outright racism and violence.

Between the beginning of this general 'migration' to urban areas and the MLK riots, white people became increasingly 'motivated' to move to the suburbs, which led over time to the urban centers deteriorating until they were completely unstable, usually necessitating rescue by the state [affordable housing, food stamps, etc]. Eventually a trickle of white development/business starts the reverse process of gentrification.

I am not aware of a single case of increase in urban development having a net benefit to the black community, mainly because they are almost never the target demographic for that development.

When people complain about shitty urban areas full of blight, homeless, mentally unstable, crime, etc, they're basically complaining about the state of the urban center which white people created when they moved out decades ago.