The secession of seven Deep South states (South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, Texas) between December 1860 and February 1861 stemmed from intertwined causes, with slavery as the central thread.
Slavery Preservation: The institution's economic and social centrality made Lincoln's anti-expansion platform existential. Secession documents explicitly cite slavery protection—Mississippi's declaration states: "Our position is thoroughly identified with the institution of slavery."
States' Rights Doctrine: Invoked selectively—primarily to defend slavery against federal limitation. The same states opposed Northern states' rights when they passed personal liberty laws protecting fugitive slaves.
Economic Anxiety: Cotton-dependent planters feared tariff increases, market disruption, and labor system collapse. "King Cotton" diplomacy assumed European dependency would force recognition.
Cultural Alienation: Divergent religious interpretations, social hierarchies, and honor cultures created separate identities. Southern nationalism crystallized around a perceived "way of life."
Political Marginalization: Demographic shifts favored the North. The 1860 election proved a Northern president could win without a single Southern electoral vote.
Fire-eaters (radical secessionists like Rhett, Yancey, Ruffin) radicalized discourse. South Carolina's unanimous convention vote (Dec 20, 1860) created momentum. The Montgomery Convention (Feb 1861) formed the Confederate States of America before Lincoln's inauguration.
Unionist sentiment persisted, especially in upland areas with fewer slaves. West Virginia eventually separated. But the confluence of economic interest, ideological commitment, and political calculation carried the Lower South into confederation.