Perhaps this is what an MLS fan range map would look like. Interested in any comments about these ranges. I've found that the MLS has a larger proportion of fans who are out of place. These 'irredentas' are fans away from home who have likely started following a team because of a particular player, an ethnic culture associated with the club, lack of a local team, or preference of playing style. I found that USL clubs besides the soon-to-be MLS teams Portland Timbers and Vancouver Whitecaps have such small fan bases that they do not deserve a territory. FC Dallas has the smallest territory: they have the fewest fans (poor stadium planning placed their stadium far from their fan base and poor marketing compared to other teams such as Houston have caused this). KC has a large range, but has few dedicated fans. LA does not seem to have a large range, but they have more supporters scattered across all other ranges than any other team. The two Canadian teams have large ranges which compose of their respected halves of their country. Chicago has fans across the midwest into Detroit, but Columbus has many Michigan fans as well due to their feeder programs. Likewise, Chicago may have more territory in Mississippi due to their feeder system and RSL may see a growing range into Arizona due to their newly established youth programs there. Houston and Chivas have soaked up the Hispanic populations in Texas and California. The Northwest is the most highly contested region; many teams within close proximity create a mesh-up of fan bases. There local geographies such as highways, rail lines, natural barriers, and cable providers may greatly influence more detailed patterns than shown above.

Overall, I like to think that this map shows that soccer has large fanbases across the US and that it is not just a regional sport. The MLB has large gaps in their ranges as well. Besides Florida, the MLS has done well to include all populations, all ethnicities, and regions.