Virginia and Mississippi in 1976

[Antonio the Sixth]

Mississipi used to be the most conservative southern state at this time, and they probably considered Carter as a liberal ( even if a moderate one ) instead of as a southerner.
Virginia has always been more republican than the country since 1952.

[Antonio the Sixth]

Yeah, increased black turnout probably was the cause; maybe Reagan's speech arguing strongly for states' rights, which occurred in Mississippi, made a difference.

Looking at the swing map, almost all of western Mississippi swung towards Carter in 1980, and that's the part of the state with the heaviest black population, is it not?

Though it's not entirely regional; some strong Carter swings in eastern MS in counties that were bordered by strong Reagan swinging counties. Probably the black/white divide again, I suppose.

Also look at the exit polls in 1976 and 1980 among blacks.  http://elections.nytimes.com/2008/results/president/national-exit-polls.html

Ford got a surprisingly high 16% among blacks, while Reagan got just 11% in 1980. 

Apparently his States Rights speech in Philadelphia and his Welfare Queen anecdote didn't exactly endear him among blacks.