So I just finished reading the main story and only skimmed the rest of the comments, so I apologize if these questions have been asked already.
First, what about Alaska? Second, a lot has been said about whites on the reservations, but what about visitors/residents from elsewhere, like Asia or the Middle East?
Lastly, I find it hard to believe that everyone is ignoring the Aztecs - or the people who will become the Aztecs. This is one of the most unpleasant pre-modern cultures to ever exist and what they could turn into once technology starts filtering down south should be worrying everyone.