On summer ball teams in Canada, there are some players from Canadian schools, which are otherwise mostly US-based players.
I looked it up. UBC plays mostly US-based teams (in the NAIA?); other Canadian college teams play each other . . . in the fall.
You might also look at the rosters of some of the Canadian schools' teams, to see how many Americans they have (UBC, for example, has very few; McGill has 7 right now).
A poster on this site used to post quite a bit about Canadian schools, see: