I'll just say they continued voting Democrat for longer than people here would believe. The strongest areas for Thurmond and Wallace in the south were some of the last counties to flip Republican, many of them took until after Bill Clinton. There's counties in northern Alabama that voted for Gore and against interracial marriage in 2000.
Um no?
I'm referring to his 1948 presidential run, where he got overwhelming majorities in 3 southern states and decent percentages in other states. Before 1948 these states voted 80+% Democrat. The fact that he was a Republican later doesn't mean many would be Truman voters voted for him in 1948.