A few nukes and too much manufacturing goes boom!
So, give tax breaks to break up the one big area. And, industries went elsewhere.
Detroit sinks because jobs left with those tax breaks building plants in other parts of the country (and world). School busing pushed Detroit residents to cities and towns with different creative names neatly placed just outside the Detroit city borders. With fewer jobs there was no one to move into the empty houses in Detroit except people who were not allowed to drive through those creatively named towns while black, the disabled, and the poor.
If you want to blame the blacks, the auto company decisions, the city's decisions, you should be treated as a fart in the wind.
Great Lakes shipping was less important than trains and trucks. Detroit being on a river did not matter as much. Iron works moved to other countries. All the trees were gone after the Detroit fire and then Chicago fire. Cast iron stoves, steel cars, logging all moved elsewhere. The boon was over.
Do auto company CEOs make mistakes? Yes, they all do. Did their SIX YEAR lead time on cars leave them hanging? Yes. It is what it is!
Were Japanese cars tighter built? Yes. But, get this, Americans did not change their oil and their cars still kept running. The Japanese car owners did change their oil and their cars kept running.
Had they not, their cars would not run as long as an American car.
Americans change their oil now. And, American cars are now better than the Japanese and have been for years.