I'm not saying that blood quantums have no legitimacy in determining "Indian-ness," but blood quantums lead to the ultimate disappearance of any Indigenous community that adopt them as the sole means of community identification. Put it simply, U.S. federal law allows Indian individuals to identify with only one Indian tribe at a time. That means if an Indian person has children by even an Indian person of another nation then her children will only
be "half" Indian!
That leaves Indian people with a peculiar problem---marry only your cousins and inbreed your people into idiocy, or marry outside and lose your federally-recognized nationhood. Some Indian nations have wisely seen the genocidal/suicidal goal behind blood quantum politics and discarded them. The Lumbee people of North Carolina have never been subjected to blood quantums and are growing fast in numbers, economic and political power, all without federal interference into how they define membership.
Long before any Indians were enrolled, before even the documents that created the United States were written, the people of this land adopted outsiders to enlarge their numbers. Indian cultures did such a thorough job of assimilating newcomers that Eurowestern society feared the appeal Indian societies had for "civilized" whites and enslaved blacks. Despite the outright propoganda dramas (popular until the 1920s as silent movies) of half-white, half-Indian tragic misfits doomed to lifelong loneliness and lovelessness, frontier governments dreaded the ability of Indian cultures to raise half-whites and full-whites to full acceptance. How sovereign is any nation if it can not even claim its own descendants and therefore guarantee its own future?
This fear played out after the final stages of conquest of the Plains and Southwestern peoples, when the boarding school system worked overtime to de-culturalize the children of our cultures. It seems the prevailing powers feared the "vanishing" Indian still represented a serious threat despite relatively
low official numbers compared to the "white" ( and therefore "inevitable") inheritors of the Continent.
INDIAN UNDERCOUNT:
At the start of the 1900s, the number of Indian people undercounted is difficult to estimate. Eastern Indian people and their white descendants who research their own families often find their ancestors listed as "mulattoes" or "free colored." Sometimes this surprise even comes out when seeing, for the first time, the birth certificates of their own parents! These individuals may have lived their whole lives in Indian communities, and never realized they were so classified. Some Indian people allowed themselves to be classified as "mulatto,' so as to avoid being forced off their land during the removal era.
Two severe blows, in rapid succession, hit the count of Indian people east of the Mississippi.
In 1920, the U.S. census stopped listing anyone as Mulatto (a category which allowed them to remain racially distinct), and instead listed them as "black," or "white" (if they were light enough). Then
in 1921, a fire swept through the building in Washington DC that contained all the census records since 1790. Coincidence?
How many mixed-blood and other Indian people were eliminated from the historical record by these two drastic changes?