SOLID SOUTH. The southern states of the United States became "solid" behind the Democratic Party following the Civil War. This occurred as a reaction against the Republicans, who had prosecuted the war for the North and inflicted upon the South the depredations of Reconstruction. As Reconstruction ended in 1877, the South quickly moved to reverse the black empowerment enforced by Northern troops and to restore a culture of white supremacy. Many white southerners realized that a united political front would be necessary to preserve this culture, and the "solid South" was the result. Southerners supported Democratic candidates for office at all levels, from president to municipal dogcatchers.
The first cracks in this unanimity appeared in 1948, when President Harry Truman, a Democrat, supported civil rights reform. Democrats from southern states (known as Dixiecrats) refused to support Truman for reelection, held their own nominating convention, and offered Senator Strom Thurmond of South Carolina as a third-party candidate.
The Solid South splintered in the 1960s, as the Kennedy and Johnson administrations, and their supporters in Congress, backed wide-reaching civil rights legislation and used federal troops to enforce court-ordered racial integration. Southerners began to return to the Republican Party, especially when voting in national elections, and the South is today regarded as a Republican stronghold.
Black, Earl, and Merle Black. The Rise of Southern Republicans. Cambridge, Mass: Harvard University Press, 2002.
Glaser, James M. Race, Campaign Politics, and the Realignment in the South. New Haven, Conn.: Yale University Press, 1996.