Unbossed has an essay full of details about the depopulated neighborhoods that fill the rust belt and their impact and economic meaning.
When I was in Buffalo, one issue seriously considered was simply disincorporating the city and returning it to unincorporated county jurisdiction. It didn't happen, but the sense of utter defeat was palpable.
We have relatively well worn paths to downsizing businesses. We have far fewer precedents for dealing with governments that are in a state of irreversible, long term population decline. It isn't that our country has no ghost towns. Brief descriptions of the ghost towns of Michigan alone fill a couple of volumes, and Colorado has some. But, it is one thing for a hamlet that barely made it into conscious recognition to give out, and it is another to see the collapse of mid-sized and large American cities across a whole swath of the country depopulate at the same time.
The essay authors despair at efforts to downsize cities by bulldozing development and ending services to whole neighborhoods, but it is hard to see a responsible alternative.