That's probably the population of the town alright but as with many provincial towns there's a large hinterland. Players from all over North Leitrim. They play in the Sligo/Leitrim league, the Leitrim bit is literally Manorhamilton as there are no other clubs from Leitrim in the league (although I think that Carrick-on-Shannon have underage teams).
Decent under age structure but Manorhamilton is more a GAA town so the soccer often suffers from that.
The under 18's won the Connaught Cup shield last year or the year before.