That total seems a little high and California births as early as 1800 (who returned to New York State) seemed a little early.
After a little searching based upon counties, I made a discovery about Clinton County, New York, and these “Californians.”
412 of them lived in Clinton County.
According to the 1850 census transcription at Ancestry.com, there were 40,049 residents of Clinton County. According to a search of their database, 412 of those Clinton County residents were born in California. That seems high–1% of the residents of Clinton County, New York, in 1850 were born in California. Did all those people move back east after spending some time in California, including some who were born in California in the 1820s and 1830s? Is there a story here?
They weren’t born in California.
Most of them were probably born in Canada. A few might have been born in Connecticut. There was not some exodus from California to upstate New York shortly before the 1850 census was taken. The migration is not the story.
Canada was often abbreviated as “Ca” in census records during this era, especially in places where many Canadians were living. Clinton County, New York, had a sizeable population of Canadian natives, including many French-Canadians. It’s also possible that abbreviations for Connecticut (“Ct”) were read as “Ca.”
The transcriber is to blame.
The transcribers at Ancestry.com were probably not typing in the location, but instead likely were choosing from a drop down menu of location choices. And, what does “CA” mean to most people today: California.
Ancestry.com standardized all the locations in their census “transcription” to in order to eventually facilitate their infamous search. There was a tradeoff when that decision was made. It required transcribers to sometimes guess what certain abbreviations stood for. Guessing is what some of them certainly did in situations like this. That’s why when describing the census transcription at Ancestry.com the word should be put in quotation marks because in some cases the location was not “transcribed,” it was surmised. They would have been better advised to transcribe in the old fashioned way:
transcribe materials as they are written
That would have meant putting “Ca” as the place of birth for these people when that’s what the census said and then the geographic features of the Ancestry.com “search” would not have been as easy to construct.
I would have lived. I could have searched for “Ca” as a place of birth because I know that sometimes that how Canada gets abbreviated. I shouldn’t have to search for births in California because “Ca” was read as that state instead of the nation of Canada.
There’s always a tradeoff.
The end result is that in some cases those of us searching the census at Ancestry.com need to throw out the place of birth when conducting a search. Because even it was right in the census and abbreviated by the census taker, a “transcriber” might have surmised it meant something that it did not.