Compare 1920 and 1992, or something.
Although the 1992 Democratic ticket of Clinton/Gore did quite well in the South compared to past Democratic tickets, since the 1964 Realignment Election contested between Johnson and Goldwater, 1992 wouldn't be a good example, due to the third party candidacy of Ross Perot. The 2000 Presidential Election would be a good example, despite Katherine Harris' dirty work as Florida's Secretary of State, but that's another story altogether.
What exactly is your point? Is it that the Republicans were once a party that primarily focused on the interests of the Northern states, and now they do vice versa by focusing on the Southern states? OMG U R A GENIUS!!!! Where on Earth do you get your insight from? Wonders never cease.....