There are 7 teams in the AMNRL, from north to south: Connecticut Wildcats, New York Raiders, Southampton Dragons, New York Knights, Bucks County Sharks, Aston Bulls, Northern Virginia (NOVA) Eagles.
And as Jim from Oz rightly stated 6 teams in the USARL.
Things in the US are still very much in the developmental stage. They improve each year, especially the playing standard but unfortunately each club is pretty much reliant on one or two individuals that do the majority of the work/finance. The 2 teams that dropped out of the USARL this year we're mainly due to their owners moving on.