Two things about us Americans: First, those of us of U.S. citizenship are called Americans because we are the only country in either South or North America that has the word “America” in its name. It's a hell of a lot easier to say “American” than “United States citizen”, though I've always enjoyed being referred to as a Yank in Britain and a running dog imperialistic war monger by everyone else.
Don Olson [1] on American Cultural Assumptions [2]
Enough said.
[1] http://c2.com/cgi/wiki?DonOlson