Ron Johnson writes:
The oldest nation[0] in the region gets to pick it's name and
abbreviation. That would be "us".
But we didn't. It was the Europeans who attached the label "american" to
first residents of the colonies and then to citizens of the United States
of America. 18th century "Americans" identified more closely with their
states than with the nation. A resident of Virginia would have said "I'm
a Virginian", not "I'm an American".