Downhill from where? Nowheresville?
There was an influx of blacks migrating from the south in order to man the production assembly lines in the automotive plants at that time and housing was needed. That was the only available land at that time that was available for housing...........
"Downhill from there"? Not hardly, the blacks who migrated to Detroit for the auto industry jobs eventually were able to purchase houses in their respective neighborhoods and became productive members of society along with the Italians, the Poles, the Irish, and the other immigrants who came to Detroit for a better life.
Sounds like you really like the 'progress' that's been made in Detroit since 1942. I'll bet you've really had some fun on "Devil's Night". Buy some of those $50 houses?