Note, indigenous people were less than 1%. New York City had the largest proportion of immigrants at 45%. Your claims of "only natives were there" and "everyone else immigrated from somewhere" are demonstrably false.
Are you being dense on purpose? The US has been a country for 250 years and the Mayflower landed 400 years ago. Most of the people were born in the US.
'*The constitutional population excludes the populations of Native Americans "maintaining their tribal relations and living upon Government reservations" and "the newly acquired district of Alaska."'
Yes. That is how they differentiated "True population" and "Constitutional population". They also have two "Indian population" line items for on and off reservation. That footnote does not mean they were not counted.
