I have never read that anywhere. Please provide the source for that info. You are aware for political purposes leftists have vastly overestimated the amount of people living in North America before the first Europeans arrived.
Usually leftists claim there were 15-25 million Indians living in NA north of the Rio Grande, and they were all almost totally wiped out by the Europeans. Little evidence exists to support that contention.
Most likely there were only 2 or 3 million people at most. The lack of big cities and buildings, the fact that there were no huge agricultural concerns, and the fact that many Indian tribes warred with one another made large populations almost impossible to attain.
FWIW, one of the reasons I became interested in Indian populations was a radical leftist sociology prof I had in college. I disliked the man intensely. His "specialty" was American Indians and he was obsessed with the idea that the American gov. was trying to murder all the Indians. Not just in the past but today as well.
After hearing his blather in class, I checked on a number of resources available. From the stuff I read it made it obvious that considering all the factors, large populations before European settlement were virtually impossible.
‘
The population figure for Indigenous peoples in the Americas before the 1492 voyage of Christopher Columbus has proven difficult to establish. Scholars rely on archaeological data and written records from settlers from the Old World. Most scholars writing at the end of the 19th century estimated the pre-Columbian population as low as 10 million; by the end of the 20th century most scholars gravitate to a middle estimate of around 50 million, with some historians arguing for 100 million or more.[1] Contact with the New World led to the European colonization of the Americas, in which millions of immigrants from the Old World eventually settled in the New World.’
https://en.wikipedia.org/wiki/Population_history_of_indigenous_peoples_of_the_Americas
‘...Within just a few generations, the continents of the Americas were virtually emptied of their native inhabitants – some academics estimate that approximately 20 million people may have died in the years following the European invasion – up to 95% of the population of the Americas....’