It is no coincidence that the rapid expansion of the league follows the explosion in attendance in recent years. While some of the growth in overall attendance is a result of the expansion as well as the longer schedule (teams went from 30 games to 34 games in 2011), we can see below that the growth of attendance has outpaced the size of the league in recent years.
The number of teams is expected to jump to 22 with the addition of another club in Miami that David Beckham will own. Not bad for a league that contracted to ten clubs just 11 years ago...
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Data via Major League Soccer and ESPN.com.