[Antoninus]

Cahokia was the hub of a way of life for millions of Native Americans before the society's decline and devastation by foreign diseases.

Uh, sounds like a bit of an exaggeration to me. This civilization may have had a wide reach, but to say it encompassed millions is an incredible stretch.

[Fraxinus]

to say it encompassed millions is an incredible stretch.

I find any number under 10 million very reasonable. This was a major civilizational center for most of what is now the eastern US. The population of the US according to the 1860 census was in the neighborhood of 60 million.