Reflecting America’s “small town” mythology and nostalgia, Money’s focus in both 2009 and 2011 was on small-to-medium sized communities (populations between 8,500 and 50,000) with a desirable location (within 60 miles of a major airport) and a modicum of diversity (less than 95 percent white). (In 2010, Money’s list looked at “small cities,” with similar criteria but a population range from 50,000 to 300,000.)
http://www.brookings.edu/up-front/posts/2011/08/25-metros-katz-washburn