Its totally socio-economic and not racial. After WW2 you had the second or third great black migration to northern cities, and despite the forced ghettoization and redlining you have black families moving into the middle class in the 50s and early 60s, like every other working-class group since the German migration. Then social welfare hits like a bomb.

It'd be the same for Italian or Irish immigrants in their ghettos had social welfare hit decades earlier. There's a reason why the deep south still has semblance of black middle class in their cities. Southern cities were poorer than their northern counterparts so blacks had an easier trip up the economic ladder to relative prosperity for their region. The north has never been properly desegregated and the concentration in wealth has always been in the northeast and midwest.