I''ll rebut my own assertion and point out that Atlanta has been doing exceptionally well as of late. Still, most majority black cities (Detroit, Flint, New Orleans, Memphis, Baltimore, Washington DC, Gary, St. Louis, Cleveland, Camden) seem to be pretty troubled.
The issue here is that it becomes a self-fulfilling prophecy. Many cities become majority-black because economic insecurity leads to fighting over municipal services which causes white people and middle-class black people to leave for the suburbs and other metro areas. The main issue here is that white people have the benefit of never having to be in the minority somewhere if they don't want to be, so they can and do always move somewhere else, either near or far, rather than compete for control of civic institutions if they're going to get outvoted.
As has been said, there are majority-minority cities which have prospered, which in turn brings in more ethnic diversity as people from other communities move back in. Atlanta and Washington, D.C. are the typical examples here. It's also true of neighborhoods within New York, Boston, and parts of California.
Camden and Washington, D.C. are light-years apart in so many ways. In fact, the cities named cover a broad range of experiences. St. Louis has many bombed out areas, but it also has many vibrant neighborhoods, and the metro area itself is troubled and has lost some of its economic anchors. St. Louis, Cleveland, and Baltimore have large ethnic neighborhoods with some political pull. Gary, Camden, Detroit, and Flint are in a different league of economic despair. Where city boundaries are drawn makes all the difference. Etc.
