Why do you think they had all different racial categories on the census forms.?
To find out where all the white people lived; it is easier to kill people when you know where they live.
Remember: the last government that took such an interest in the racial classification of its citizens eventually ended up sending a few races to the gas chambers.
Also, the 1940 census was used to find Japanese Americans so they could be sent to internment camps:
The census bureau says “we will never do that again”....
Never again....
Never again....
Those words sound so hollow these days.
They have always asked for race on the census form since the first one which listed all individuals (1850). The 1850 census did not provide the given names of slaves but still gave their race (B or M).