This is serious business in the South, where Southerners have abandoned the Democratic party for what the Republican party now stands for. I believe Eisenhower (R) started it and Reagan (R) completely captured the South for the Republican party.
Outcome of November elections in Louisiana will be interesting and informative.
As for your other thought about the South drifting into our column, I think it was more like Nixon that accomplished that in 1968
Well, that was my take on it, but these maps seem to indicate the big crack came in 64 with Goldwater. Then it reverted until years later, 1972 to be exact. Now wild cards Wallace, Carter, and even Clinton didn't help any. It actually didn't settle completely until 1980, with Reagan's first General Election win. Then Clinton made some reverse headway.
Check out these voting map graphics: (just for informative purposes, it's interesting...)