Detroit was a major powerhouse, wealthy and prosperous in the early part of the 20th century. I had always believed the narrative of white flight creating the poverty in Detroit (and other rust belt cities), but perhaps I had downplayed the effect that changing patterns of employment had on the city's fortune. Read these snippets from the wikipedia article on Detroit:
"Industry spurred growth during the first half of the 20th century as the city drew tens of thousands of new residents, particularly workers from the Southern United States, to become the United States' fourth largest."
"The gasoline crises of 1973 and 1979 also impacted Detroit and the U.S. auto industry as small cars from foreign makers made inroads." [Wikipedia]In Baltimore (7th most dangerous city), when the Bethlehem steel plant closed the jobs went away and never came back. There, the economic disruptions laid a significant blow to the city that was very hard to repair.
Again, the consequences of changing value of labor are significant and lasting.