Either 1936, 1940, or 1944 if I had to guess. I know that either Lyndon Johnson in 1964 or Bill Clinton in 1996 was the last time the Democrats won the white vote overall. I recall reading that the only states where the Democrats won the white vote in 2020 were Massachusetts, Vermont, Rhode Island, New York, Maryland, DC, Virginia, Illinois, Colorado, Washington, Oregon, California, and Hawaii.
What about NH, Maine and Minnesota. I'm fairly sure Biden carried the white vote in those states.
In Virginia for sure and maybe.. Illinois the white vote went Republican