I think the use of the term "American" to refer primarily to individuals from the United States of America may be in large part because "United Statian" sounds really fucking weird when you say it out loud, and even looks strange written down, assuming I even spelled it right (and that it's even a real term, which I strongly doubt). I wish I knew of a better term to use for persons from the U.S.A., so that "American" could be used more widely for all individuals from the continents of North America and South America without mass confusion...