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

This action followed the election of Abraham Lincoln, who opposed the expansion of slavery into new territories. South Carolina's secession was driven by a desire to protect its interests and maintain the institution of slavery, which was integral to its economy. The move set off a chain reaction, as other Southern states followed suit, ultimately leading to the formation of the Confederate States of America and the onset of the Civil War.