What killed the democrats in the white south?

[Orser67]

1)It started with civil rights, but in 1948, not 1964. Between 1880 and 1948, the South pretty much always went Democratic in presidential and Senate elections (though Hoover did win a few Southern states in 1928). Starting with Strom Thurmond's 1948 third party run (which was in reaction to the Dems' 1948 civil rights plank), Democratic loyalty started to fray. Democratic leaders started defecting to Republicans after the signing of the 1964 civil rights bill; Thurmond switched parties literally two months after the signing of the civil rights bill, and other Democrats followed. In 1963, there was one Republican Senator from the former Confederacy (John Tower of Texas); by 1969, there were five. By 1981, there were ten Republican Senators from the former Confederacy.

2)Congressional Democrats were able to hold to the South in a time of unpolarized parties; it was easy enough for them to differentiate themselves from the national brand in the 1970s and 1980s. By the 1970s Republicans were winning white Southerners; Carter was able to win Southern states in 1976 only by constructing a coalition of blacks and relatively moderate whites. As the parties polarized after the 1960s (on social, economic, and racial issues), more and more Democrats became vulnerable, and Congressional Democrats lost a lot of Southern seats in the Republican wave elections of 1980 and 1994.

3)As the Republicans became the dominant party in the South, more and more Democrats either switched parties or lost re-election. An unpopular (in the South) president spelled the end of a competitive Democratic Party (at least at the federal level) in most Southern states in 2010 and 2014.

[smoltchanov]

IMHO - combination of some reasons, almost all of which were already mentioned here:

1. Civil Rights (since 1948). For many Southern Democrats of the past it was a "betrayal of principles". South was a segregationist country for more then 50 years, dilligently voting for Democrats on all levels,  and here "it's own" party destroys a "pillar" of Southern society.

2. Gradual transformation of Democratic party from populist (but with tolerance for social conservatism) to less populist and much more socially (and foreign policy) liberal one. With Blacks being not even "major", but "main" faction of the party, especially - in the South. Many whites simply doesn't fathom himself being a members of "Black party"

3. Dying out of older people and older loyalities  and other demographic changes (mass migration of people from the North, who, frequently, had no loyalities to Democratic party)

4. It's simply advantageous now to be a member of Republican caucus in most of the Southern states now. You get all the pluses of being in majority (committee chairmanships, and so on). People like Louisiana's John Alario can't be really called an "ultraconservatives" (unlike, may be, people like James Fannin), but they really want these priviliges. There are almost no pluses to run as a conservative Democrat and then be in dire minority now (that's why expect John Milkovich to switch at some moment)

5. Nationalization and extreme polarization of politics. Even 20 years ago you could serve in Mississippi's legislature as very conservative Democrat (to the right of half Republicans at least), and it was "normal". No more...

Plus - some other factors...