This study from bizjournals.com analyzes the nation’s biggest metro areas and their capacities for supporting professional sports franchises. The study looks at metro area population, as well as the combined personal income of the area’s residents, which is of course one of the major factors big sports look at to determine franchise location (the other being whether or not local politicians can be bullied into paying for new facilities). Not surprisingly, Los Angeles ranked as the #1 target market for new sports franchises, as the departure of both its NFL teams in 1995 left it with a huge surplus in personal income. The #1 most over-saturated market was Tampa-St. Petersburg.
A chart with team-support statistics for 179 metro areas can be found here.