USian?

I've just read yet another article where the author refers to us (citizens of the United States of America) as "USians".

WTF?

Okay, so maybe I'm behind the times, but I just don't get this. People seem to use this so they make it clear they're not talking about Mexicans or Canadians. But neither Mexico nor Canada have "America" in their names. Mexico is officially Estados Unidos Mexicanos (United Mexican States) and Canada is, well, Canada. The US is "The United States of America". So how could anyone of any intelligence mistake "Americans" for Mexicans or Canadians?

Okay, so mini-rant over. Probably just a by-product of my massive cold which is making me extremely cranky...