Why did the South switch parties?

[smoltchanov]

To make it simple for the small brains on this site: it was the blacks, you see.

CORRECT answer. But not FULL answer...

[smoltchanov]

The single most salient reason, after some urban areas in the South like Dallas started voting for the GOP, is that when blacks began to be allowed to vote, the "Tory" Democrats could no longer control the Dem primary results in the South, and thus over time decamped to the Pubs.

And that too. May be it's really THE most important reason. But, surely, not a SINGLE reason..

[smoltchanov]

Basically, it was a combination of white backlash against the Civil Rights Act of 1964, increased levels of income and wealth, a corresponding increase in the population of metropolitan areas at the expense of rural areas (with Northern white conservative migrants making a fairly significant contribution here), the  transformation of white racial attitudes from being openly racist to being more "colorblind" in light of whites believing that civil rights issues had basically been "solved" and thus, whites being opposed to the expansion of civil rights protections against de facto segregation and inequality (as opposed to de jure segregation and inequality), the decline of the white populism of  the downtrodden in favor of the white populism of the upwardly mobile middle class and aspiring middle class, the rise of the Religious Right - which made the white evangelical Protestants who dominated Southern culture a political force to be reckoned with -, generational replacement (how many Southern whites who are alive today remember the New Deal? lol), and finally - as Torie alluded to - the Voting Rights Act precipitating the collapse of the white Democratic machines that had made the South effectively a one-party region (with their collapse creating an actual two-party system in the South in which black voters were increasingly influential within the region's Democratic Party).

And THIS (IMHO) is at least close to complete explanation....

[smoltchanov]

The Republicans switched platforms.

Democrats switched more. During FDR time there was almost no mentioning of Black's civil rights in Democratic platform. Of course, Roosevelt's programs helped a lot of Blacks, and he himself was, undobtlely, pro-civil rights, but, as cinically this may sound, he had other (also most important) problems, which needed to be taken care of, and he needed rather solid (and even that began to decrease to the end of his term) southern support for that. Contrast  with strong (especially - by THAT time standards) Democratic civil rights platform of 1948 is VERY clear. Before 1948 few southern Democrats thought about "alternatives" (Texas "Regulars" come to mind immediately, and, yes, there was anti-Catholic Smith backlash even in 1928, but these were isolated cases), but since 1948 search for "alternatives", and gradual understanding that "Democratic party is irrevocably changed", settles in mind of white Southern elites... And long process, mostly (some conservative white counties are STILL conservative Democratic on local level) completed by now, began..

[smoltchanov]

Its not as simple as a Black/White thing I don't think. After the 1994 Republican Revolution some Conservative Dems in the US House felt more in line with Republicans on fiscal issues I guess. Many Southern State Legislatures didn't switch over to Republican Control till the Y2era as the Virginia State Legislature was the first Southern State to switch over to complete Republican Control in 2000. The State Senate was in Spilt Control in 1996-1997 as the 2 parties agreed to  "Power Sharing Control" as the Dems retained a slim majority in the" House Of Delegates" 52D-47R, and 1I. In 1998-1999 the Republicans gained control of the State Senate and the 2 parties were tied in "The House of Delegates" 50D-49R, and 1I but the Dems retained the Speakership through another "Power Sharing Agreement".

It is fact that alot of White Evangelicals switched over to Reagan in 1980 after supporting Carter in 1976. They felt Carter was a failure.

That's too of course. Carter was the last "rural southern Democrat" (and, by present day standards, at least somewhat conservative) white southerners initially believed. In general i see some "realigning waves", which, combined, led to present situation:

1. Very timid attempts before 1948 (anti-Catholic 1928, "Texas regulars" of 1940, and so on)

2. Dixiecrat movement of 1948 after passing strong civil rights platform in Democratic program

3. Goldwater candidacy of 1964.

4. Reaganisation of Republican party and Reagan's campaigns of 1976 and 1980

5. Republican wave of 1994 and Gingrich's "Contract with America"

6. Republican wave of 2010 (which, essentially, finalized present situation, 2014 only added some ultrafinal details).

Of course - demographic and economic changes went continuosly all this period too, but politically it's mostly appeared as a serious of waves approximately each 16 years...

.