Our list finds that median household income doesn't determine startup success.
Why? "There is a reasonable hypothesis that areas that are fertile for startups are fertile at a point in time, such as Detroit in the 1890s," says Ed Glaeser, Eleanor Glimp Professor of Economics at Harvard. "Startups come, they succeed, and then it becomes progressively less friendly as the area becomes wealthier. A few dominant firms emerge and they eventually end up pushing out startups. Areas then have to find a way to reinvent themselves."
[Twenty Dollars Image via Robert Pernell]
A version of this article appeared in the May 2013 issue of Fast Company magazine.