The politics of the political parties changed more than the politics of the states. Vermont + Massachusetts used to be solid republican states. South Carolina was 98% democratic in the 40's. Civil rights was one of the main reasons for the flip.
MA was a Democrat state since 1928. Vermont's change wasn't as clear-cut, but the slide to the Democratic party began during the 1950s.
And how many times will the lie that the Civil Rights movement caused the South to vote GOP be repeated?? In 1948, the South went with the Dixiecrats; in the '50s and '60s, they voted for "Unpledged Democrat Electors." The only GOP vote was Goldwater in '64, then the next election they went with Wallace. Discounting Nixon's '72 win, the South single-handedly elected Jimmy Carter, a Democrat.
If anything, the South tried every conceivable mean to
avoid voting Republican in 40 years.
