It's only recently become popular for white folks to admit to Indian ancestry. Black folks have been into that for more than a century.
Now, how many white folks have Indian ancestry in this country. Well, to start with, there's a genetic marker ~ shovel teeth. If you got 'em and have no known East Asian or Cossack ancestry, you're in the zone ~ and that has been known for years to be 2%. Since that's an autosomal recessive, there'd be another 2% with no shovel tooth gene at all, and 4% with a recessive gene that could be identified. That's a grand total 8% of the white population have to have an American Indian ancestor.
That'd be well over 15 million people! The recognized tribes have no where near that number of members.
Going well beyond that group, there another 9 million white folks who have some or a lot of Sa'ami (Laplander) ancestry in this country. That's roughly 100 times the number of Sa'ami in Europe!
We have groups of blacks in New Orleans who dress up in magnificent Indian garb every Mardi Gras and parade a route. These blacks identify emotionally or physically with American Indians and are proud of it. It would be really interesting if everyone in the South knew their real heritage because they would find a lot of mixed blood in their veins, I am sure. I for one, may have a bit of black blood because (now this is just 3rd party here say) on my mother's side her uncle in Mississippi had a farm and supposedly inpregnitated a black worker then raised the boy in his family. I don't know that to be a fact but I am sure that happened a lot in those days. It doesn't bother me at all because the more the mixture the richer the past, I say.