A look at the census provides a good example of...

“A look at the census provides a good example of this bias in historical records. The census enumerators in 1910, for instance, were instructed to use so-called Indian Schedules “principally for the enumeration of Indians living on reservations or in tribal relations.” They were given further instructions on how to group mixed communities. “Every family composed mainly of Indians should be reported entirely on this special schedule, and every family composed mainly of persons not Indians should be reported entirely on the general population schedule.”
This presented a problem for some Indian communities, particularly those with any African ancestry. People of mixed black, white, and Indian ancestry were classified as mulattoes by the 1910 census, undifferentiated from people of solely white and black ancestry. Surrounding populations in Louisiana acknowledged Indian ancestry in multiracial tribal communities by addressing them as Redbones, a derogatory term that denotes Indian, black, and white ancestry. The official census record, however, did not have a category to reflect that distinction, leading one to conclude that the record stated they were solely black and white instead of Indian. Often, the extent to which a community designated as Redbone had mixed at all was questionable, as in the case of one Louisiana tribe, who were dismissed from consideration of federal services in 1938 by anthropologist and BIA official Ruth Underhill not so much because they had mixed with blacks but because local whites said they had. This characterization of them as a group with an ambiguous identity leaves the impression that they are not, in fact, a legitimate Indian tribe and therefore not worthy of federal assistance. It was a means of disempowering Indians. Tribes knew this and sought to avoid it.”

Brian Klopotek, indiVisible: African-Native American Lives in the Americas, pg. 87-88 (via a-lostbird)