In 1790, the first federal population census was taken in the United States. Enumerators were instructed to classify free residents as white or "other." Only the heads of households were identified by name in the federal census until 1850. Native Americans were included among "Other;" in later censuses, they were included as "Free people of color" if they were not living on Indian reservations. Slaves were counted separately from free persons in all the censuses until the Civil War and end of slavery. In later censuses, people of African descent were classified by appearance as mulatto (which recognized visible European ancestry in addition to African) or black. 

By 1990, the Census Bureau included more than a dozen ethnic/racial categories on the census, reflecting not only changing social ideas about ethnicity, but the wide variety of immigrants who had come to reside in the United States due to changing historical forces and new immigration laws in the 1960s. With a changing society, more citizens have begun to press for acknowledging multiracial ancestry. The Census Bureau changed its data collection by allowing people to self-identify as more than one ethnicity. Some ethnic groups are concerned about the potential political and economic effects, as federal assistance to historically underserved groups has depended on Census data. According to the Census Bureau, as of 2002, over 75% of all African Americans had multiracial ancestries.
and later?
Native Americans were included among "Other;" in later censuses, they were included as "Free people of color"