The Republicans had consistently attracted large numbers - often a majority - of the Black voters in the South, from the late 1860s onward. But in order to have more victories, the GOP also wanted white voters.
The ‘Southern Strategy’ was the Republican Party’s attempt to crack the bloc of segregationist voters to whom the Democratic Party was fiercely loyal. The whites of the deep South had voted reliably Democrat, also since the late 1860s.
This, then, was the Republican Party’s ‘Southern Strategy,’ and it was probably a factor in the Nixon victories of 1968 and 1972.
But there was an earlier plan, on the part of the Democratic Party, which could also have been called a ‘Southern Strategy’ of a sort.
From the 1860s onward, any hope for the Democratic Party in national electoral politics was based on the party’s solid hold on the segregationist and secessionist deep South. As the Republican Party had a solid foundation among the South’s African-American voters, so the Democratic Party had its base among the whites in the South, who were still angry about the Reconstruction-era civil rights which the Blacks had obtained.
Explaining how the Democratic Party played on the racism of its base, Patrick Buchanan writes:
How did presidential nominees like Al Smith and FDR of New York and Adlai Stevenson of Illinois sustain the allegiance of northern liberals and Southern segregationists? By balancing progressive candidates with Southern or border-state segregationists on every national ticket between 1928 and 1960, except 1940. Those vice presidential nominees were Joe Robinson, of Arkansas, in 1928; John Nance Garner, of Texas, in 1932 and 1936; Harry Truman, of Missouri, who had flirted with the Klan, in 1944; Alben Barkley, of Kentucky, in 1948; John Sparkman, of Alabama, in 1952, who would sign the Southern Manifesto denouncing the Brown decision; and Estes Kefauver, of Tennessee, in 1956.
The African-American voters of the era understood the Democratic Party’s commitment to its segregationist base, and so the Republican Party received a steady majority of Black votes.
The Democrats, meanwhile, experienced considerable success, with party leaders like Orval Faubus, George Wallace, and Lester Maddox.