Covered above, but, yeah, first is that bit that Latinos got grandfathered in, so a surprisingly large chunk of the population isn't what people think of when they hear 'Native American". There were also many people that were kept, or that moved in, that were "1/64th Cherokee" or the like, whiteboys who the NAN government looked the other way for due to their having some aspect, such as being a big scientist or having mojo.
"Hey, I want to apply for membership. I don't know what tribe."
"Do you have any documentation?"
"Well, no, but..."
"Denied."
"Wait!"
"What?"
"Well, I figure I gotta be part Indian. I mean, I can do this." *hands start to glow*
"Ahh. Clearly a Shaman of the, uhm. Let's go with Chickasaw. Take this letter down the hall and go to the green door. Welcome to the Nations, brother."
The assorted NAN nations had different levels of "Purity!" cries, with teh Ute being the most expulsion-happy, then the Sioux, muttermutter, and the PCC being the least trigger-happy. In some areas, people wouldn't, or couldn't, move, so the NAN allowed some to stay on by adopting them into tribes, or by letting them form new tribes, while others were set up on reservations, so that they could live in relative peace and follow their native customs, like cookouts and the Chicken Dance, and to maintain their own language in the wake of a general reculturization.
What you wind up with is a sort of blood-segregation, where those who have the most Native blood 'naturally' rise to the top, getting most positions of power and wealth, mixed-blood sorts who make up the majority of the population, and then people with no Native or Latino blood pooling arond the bottom rungs of society, if they even participate at all. When moving through the former Wyoming, for instance, you'll stumble onto the rare reservation with a couple hundred white people, living in ramshackle trailerhomes, growing crops and living off the land, trying not to cause any trouble.
The cities are still around, and filled with people (Vancouver! Las Vegas! Boise!) but the population was considerably lower than before. Mind you, it's been 60 years, and that, combined with the NAN being accepting of Meta immigration for a while, has boosted their numbers a bit. (They also tend to lie about thier population numbers, which the NAN books reported as fact, which resulted in much derision.)
Heck, a few weeks ago, I had a blue-eyed, blonde-haired Mr. Johnson to give the team a job. They figured he was Ares, but he was actually working for a NAN member. It's fun to play with perception.
