Every city that is large enough to house a lot of the very poor who have the vote are going to be horrid in crime and easy prey for the bread and circus mentality of corrupt politics, where the maintained become useful mostly for their votes. Happened in the Subura in Rome, happened in every big city that I can think of where the poor could vote.
Why should we be surprised that Detroit, New Orleans, D.C., Balitmore and so on are like that? It was like that before the welfare system got very big, too, with the local political machine directly dealing out the goodies more often and taking care of their voters. It's not new in this country at all...but because of the politics of race, it's easier to see, perhaps.
Add Atlanta, Savannah GA into that list.