Like any area, you'll find more competition in the larger metroplitan areas and less outside of the city areas in suburbia and rural areas.
Take a look at the tax rates of the areas and the population trends. Obviously one can set up a successful practice in an urban, higher tax rate area with a trending population decline, but it's more than likely to be more difficult than in growing, more business areas, especially if you can find a more rural area with less competiton.
As for your Detriot reference, did you see the news piece yesterday where the Gov of Michigan ISN'T ruling out letting the city of Detroit go bankrupt?? I'm not so sure that I'd want to look into setting up a practice in the Detroit area in the near future. They've got some more than likely rough times ahead 😱