from the attached Wiki page...
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Roots (1961–1972)[edit]
In the early 1960s, leading Republicans including Senator Barry Goldwater began advocating for a plan they called the Southern Strategy, an effort to make Republican gains in the Solid South, which had been pro-Democratic since the American Civil War.[36][37] Under the Southern Strategy, Republicans would continue an earlier effort to make inroads in the South, Operation Dixie, by ending attempts to appeal to African American voters in the Northern states, and instead appeal to white conservative voters in the South.[38] As documented by reporters and columnists including Joseph Alsop and Arthur Krock, on the surface the Southern Strategy would appeal to white voters in the South by advocating against the New Frontier programs of President John F. Kennedy and in favor of a smaller federal government and states' rights, while less publicly arguing against the Civil Rights movement and in favor of continued racial segregation.[37][39][40][41]
Congressman and Republican National Committee chairman William E. Miller concurred with Goldwater and backed the Southern Strategy, including holding private meetings of the RNC and other key Republican leaders in late 1962 and early 1963 so they could decide whether to implement it.[42] Overruling the moderate and liberal wings of the party, its leadership decided to pursue the Southern Strategy for the 1964 elections and beyond.[43]
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As for modern day Democrats, they are solidly behind Voting Rights for ALL Americans...including African-Americans...the GOP...not so much.
Link: https://en.wikipedia.org/wiki/Southern_strategy