Since the first U.S. Census in the year 1790, the 'rules' concerning Race and Ethnicity have changed greatly.
"The nation's first census was a count of the U.S. population as of Aug. 2, 1790. U.S. marshals and their assistants were supposed to visit each U.S. household and record the name of the head of household and the number of free white males, other free persons and slaves in each household. A total of 3.9 million people were counted in the first census."
It used to be the U.S. Census was taken by enumerators, it wasn't like it is today where citizen's fill out their own census forms. So in the old days no one really knew what the enumerator showed as race. I can't imagine my forefathers/mothers being asked what race they were and answering "Free Other".
"Today the Census Bureau collects race data according to U.S. Office of Management and Budget guidelines, and these data are based on self-identification. People may choose to report more than one race group. People of any race may be of any ethnic origin."
http://www.census.gov/topics/population/race/about.html
Here is an interactive timeline compiled by the U.S. Census Bureau, showing the history of Race and Ethnicity by census year from 1790 to 2010:
Measuring Race and Ethnicity Across the Decades: 1790-2010
I compiled a list of my direct Collins paternal line from copies of the original U.S. Census from 1790 to 1930. The results are interesting:
My direct paternal Collins line as enumerated by ‘Race’ on the U.S. Census
Valentine Collins
1790 Wilkes Co NC White
1800 Ash Co NC Free other
1810 Not on any US Census records
1820 Floyd Co KY Free Person of Color
1830 Floyd Co KY Free White
1840 Morgan Co KY Free White
David Collins
1840 Morgan Co KY Free White
1850 Johnson Co KY no race listed (same for David’s son Hiram)
1860 Johnson Co KY no race listed (same for David’s son Hiram)
1870 Johnson Co KY All listed as Indian
1880 Johnson Co KY All listed as Mulatto
1890 Johnson Co KY no Census records
1900 Johnson Co KY White (Andrew B. Collins and family)
1910 Johnson Co KY Mulatto (Andrew B Collins and family)
1920 Johnson Co KY White (Andrew B Collins and family)
1930 Lewis Co KY White (Timbrook Collins and family)
After 1930 always shown as White
It might be a good idea for family researchers of families with a similar mixed race background to make a list like this for family records.