The basic agricultural economy of the Old South, which was abetted by the climate and the soil, led to the introduction (1617) of Africans as a source of cheap labor under the twin institutions of the plantation and slavery. Slavery might well have expired had not the invention of the cotton gin (1793) given it a firmer hold, but even so there would have remained the problem of racial tension. Issues of race have been central to the history of the South. Slavery was known as the "peculiar institution" of the South and was protected by the Constitution of the United States.
The Missouri Compromise (1820–21) marked the rise of Southern sectionalism, rooted in the political doctrine of states' rights, with John C. Calhoun as its greatest advocate. When differences with the North, especially over the issue of the extension of slavery into the federal territories, ultimately appeared insoluble, the South turned (1860–61) the doctrine of states' rights into secession (or independence), which in turn led inevitably to the Civil War. Most of the major battles and campaigns of the war were fought in the South, and by the end of the war, with slavery abolished and most of the area in ruins, the Old South had died.
The period of Reconstruction following the war set the South's political and social attitude for years to come. During this difficult time radical Republicans, African Americans, and so-called carpetbaggers and scalawags ruled the South with the support of federal troops. White Southerners, objecting to this rule, resorted to terrorism and violence and, with the aid of such organizations as the Ku Klux Klan, drove the Reconstruction governments from power. The breakdown of the plantation system during the Civil War gave rise to sharecropping, the tenant-farming system of agriculture that still exists in areas of the South. The last half of the 19th cent. saw the beginning of industrialization in the South, with the introduction of textile mills and various industries.
The troubled economic and political life of the region in the years between 1880 and World War II was marked by the rise of the Farmers' Alliance, Populism, and Jim Crow laws and by the careers of such Southerners as Tom Watson, Theodore Bilbo, Benjamin Tillman, and Huey Long. During the 1930s and 40s, thousands of blacks migrated from the South to Northern industrial cities.
Since World War II the South has experienced profound political, economic, and social change. Southern reaction to the policies of the New Deal, the Fair Deal, the New Frontier, and the Great Society caused the emergence of a genuine two-party system in the South. Many conservative Southern Democrats (such as Strom Thurmond) became Republicans because of disagreements over civil rights, the Vietnam War, and other issues. During the 1990s, Republican strength in the South increased substantially. After the 1994 elections, Republicans held a majority of the U.S. Senate and House seats from Southern states; Newt Gingrich, a Georgia Republican, became Speaker of the House.
During the 1950s and 60s the civil-rights movement, several key Supreme Court decisions, and federal legislation ended the legal segregation of public schools, universities, transportation, businesses, and other establishments in the South, and helped blacks achieve more adequate political representation. The process of integration was often met with bitter protest and violence. Patterns of residential segregation still exist in much of the South, as they do throughout the United States. The influx of new industries into the region after World War II made the economic life of the South more diversified and more similar to that of other regions of the United States.
The portions of the South included in the Sun Belt have experienced dramatic growth since the 1970s. Florida's population almost doubled between 1970 and 1990 and Georgia, North Carolina, and South Carolina have also grown considerably. Economically, the leading metropolitan areas of the South have become popular destinations for corporations seeking favorable tax rates, and the region's relatively low union membership has attracted both foreign and U.S. manufacturing companies. In the rural South, however, poverty, illiteracy, and poor health conditions often still predominate.