These unique records of Indian Reservations were taken annually whenever possible. This means it is a unique opportunity to really take a close look at family and community dynamics during those periods.
Indian Reservations were not included in the regular U.S. Census before 1900 (with a partial exception in the 1890 census. The reason for this is that Native People living on the reservations were "Indians not taxed." Most of them were citizens of their tribe, not the United States. U.S. Citizenship happened for most Native Americans in Indian Country in 1923. Still, some were not yet citizens until the 1950's or later.