What I found of John Calvin in the 1930 Census was somewhat speculative, as the age is just slightly off but I "think" he was in California at that point:
California > Placer > Township 9 > District 18 > 4
I may have been unclear in what I meant about the ancestry, as I was speculating that John's mother was Cherokee and his father "white," as it was John's mother who was born in Oklahoma and his father in Pennsylvania. I knew that Grace was "white" from family knowledge.
My mother knew that there was some Native American ancestry on her side of the family, she just didn't know that it was as near as her own mother being listed as Mixed Blood Cherokee.
I understand what you mean about census takers speculating on race by appearance. I think that it may have been noticed and properly noted in the 1930 census because they were in the Yakima, Washington, area and that area has many Native peoples due to the tribes in the region so the question was probably asked more often or the census takers more aware of Native peoples.
I find family history fascinating because I know so little of my own. It doesn't help that not very much was passed down through family story-telling.
I would love to be able to find out who exactly John was, and who his parents were, all that good stuff.