even if the official title is Estados Unidos Mexicanos

Thanks for clearing that up, Xara. Also, it's nice to find someone else who uses a phrase like "India Indians." My Dad was born 90 kilometres north of Delhi, and lived in Quetta for most of his childhood, so like you, I'm careful to use "Native American" - at least as much for clarity as for courtesy. I have a very English friend whose grandmother happens to be Lakota Sioux, and this friend would never call her Lakota family "Indian."