South Carolina was the first state to secede from the Union, doing so on December 20, 1860.

South Carolina was the first state to secede from the Union, which it did on December 20, 1860, following the election of Abraham Lincoln as president. South Carolina's secession was a pivotal moment in the lead-up to the American Civil War, as it sparked a chain reaction of other Southern states following suit. The state’s decision was rooted in issues surrounding slavery and states' rights. This act of secession led to the formation of the Confederate States of America, with South Carolina taking a leading role in the Confederacy. The secession helped set the stage for the Civil War.