It all depends on context. There are planty of circumstances in which people from other counties in the New World might refer to themselves, or be referred to, as Americans. Not, I would imagine, at passport control.

My point? Clarifying my meaning in a discursive thread. The lack of an exclusive term for the citizens of the USA is not particularly significant, but it's an interesting enough and extremely unusual anomaly among countries. Nothing wrong with the occasional anomaly.