Interesting factoids: FC Cincinnati in the USL (the US equivalent of the Championship League in the UK), has an average attendance this year of 25,000. That would put them 15th in Premier League attendance. The top team Atlanta is averaging 52,400, for 7th in the Premier League, and Seattle is 40,500 for 9th place. Total attendance for 23 US MLS teams is at 4.7 million, less than half way through the season. The Premier League attendance last season was 14.5 million for 20 teams. I'd say thus far Football is doing decently well in the US, and the academies are just getting started cranking out talent.
Ed.: Atlanta just set a new MLS attendance record vs. Seattle: 72,243. If that becomes normal, they'll be just shy of Man U.