Neato point... Dan *is* Canajun afaik! But this country is a remnant of the British Empire, and Imperial English (this is a preferable term to "UK" or "British" English, although equally generalized).
Maybe eleven out of twelve or more "Americanisms" are actually of British origin anyway. The best way to identify the obvious cases of this is to consider the *age* of the word. If it was in use prior to the late eighteenth century, it cannot really be an "American" usage: think the likes of "closet", "normalcy", "plow", "aluminum" etc. which are commonly misconstrued as American, when in fact they are *older* words, or *older* forms of the word.
"'Real' Americanisms" are more likely descended from Yiddish or Spanish.