Forget it, Another Jazz2 Fan (and JJ Tublear, Europe is more like a continent than what you call "province", heh!).
In my opinion, Jazz Jackrabbit 2 originated from the european demoscene of which Arjan and his dutch-belgian group Ultraforce were a pretty famous part (they made Vectdemo in 1991, one of the milestones at that time). For example, the first time i learned about JJ for example was in 1993, when i read an diskmag (the diskmaggy was "Worldchats 1" by finnish overrulers Future Crew, btw) article from Arjan about an "upcoming arcarde game" he was about to release for Epic. So iMHO the game is European :-)
Nevertheless, Nick Stadler, CliffyB and Robert A Allen who did some important parts on Jazz1 and 2 are from the US and also worked for Epic, afaik. So thats the USA part :)
Arjan (who coded the core of both games, in JJ2 together with Michiel Ouwehand, who is also dutch) always stayed in the beautiful Netherlands, even if big money in the US was attracting and he is still working in Amsterdam (at LostBoys). Alex Brandon and Jeh are from the UK, btw (but they both moved to the US afaik...big money eh :-).
Well, despite dutch company Orange are the real *core* developers of the Jazz games, US-based Epic's role was very important and they were the main actor in this game (they also owned and own the right).
Apart from that, JJ2 was also first released in Europe, then in the US and i think the main market for JJ2 always was the Netherlands (and i suppose Germany is the second most important, it sold pretty okay here too i think).
As for Jazz2 online players, i think its about 60% Europeans and 40% Americans. Wild guess.

Oh yeah, and type ARJAN in JJ1. Those guys are elite. *sigh*