It has always frustrated me finding an appropriate name for citizens of the United States of America. We have the United States of Brazil (Brazilian) and the United States of Mexico (Mexicans) and we have the United States of America (Americans). Wikipedia calls us Americans, but that doesn't seem quite right, as Brazilians and Mexicans are also Americans.
You can hone it down to North Americans, but you still have a little problem with the Mexicans and Canadians, who are also North Americans. Not to count the French who live on St. Pierre and Miquelon.
So what are we to do? It's too much of a mouthful to call ourselves United Statesians, and even then we have the problem as Brazilians and Mexicans are also United Statesians.
So what's the solution? United States of Americans? USAians? Unitarians?