The Smithsonian's very first foray into ancient archeology was a smash success. Mr. Hopewell then proceed to showed them more... which, sparked an epoch of phenomenal "discovery" in the American midwest, eventually mapping 2,500+ sites...
Squier and Davis included a large collection of survey maps and descriptions of ancient artifacts that provided insight into these ancient cultures—making the Smithsonian Institution's choice of Ancient Monuments of the Mississippi Valley, as the first-ever publication on any subject, a very interesting selection. Rather than providing answers, the Squier and Davis report and research would raise questions ...
In the wake of Squier and Davis’s report, questions were still looming about who the people were that built such amazing earthwork structures and mounds, which provided evidence of an understanding of higher mathematics, advanced engineering, and the cosmos?
In the 1998, republication of Ancient Monuments by the Smithsonian, David J. Meltzer stated: “[the Smithsonian's future] was riding on a book devoted to the questions of the origin, antiquity, and identity of the Mound Builders.”
These questions became a problem for the USA, because as the country pushed westward, in pursuit of "Manifest Destiny" they kept breaking treaties with Native American populations, fordably removing them time and again from reservations and lands the USA promised to give them "forever". Fundamentally, the general public will not support military removal of "Indians" who have advanced culture, mathematics, engineering & astronomical sciences... but, them will if they are simply "savages"
Going back as far as Hernando Cortez, the advantages of NOT noticing the culture of the natives was rewarded. Under Catholic rule, any lands that where populated by civilized people, had to have ambassadors/treaties and join the Spanish empire. But lands populated by "savages" could be treated differently, including forced slavery.
So... when Moctazuma corrected the Spanish priests about the fact that Christ was crucified, not on a "T" shaped cross, but on a cross bar, hoisted upon a tree... (see https://www.lds.org/scriptures/nt/acts/13.29?lang=eng&clang=eng#p28) Cortez realized that he was in trouble, and simple ordered the cities library burned to the ground. Literally millions of Aztec codifies destroyed - today only a few dozen have survived. (https://commons.wikimedia.org/wiki/Category:Mesoamerican_codices)
200+ years later, USA politicians found themselves in a similar situation... they could not remove an educated/cultured people from their traditional lands in the Mississippi River valley. So, they had to change the narrative, and they hired John Wesley Powell to do it.
Item #2 - from "page 2" of the Smithsonian's Current Official statement;
"The physical type of the American Indian is basically Mongoloid, being most closely related to that of the peoples of eastern. central, and northeastern Asia. Archeological evidence indicates that the ancestors of the present Indians cane into the New World - probably over a land bridge known to have existed in the Being Strait region during the last Ice Age - in a continuing series of small migrations beginning from about 25,000 to 30,000 years ago"
Unfortunately, this has became the "official" scientific position of the USA, and allowed the moral justification for their treatment of Native Americans for the last ~150 yrs +/-
http://www.utlm.org/onlineresources/smithsonianletter2.htm