In 1860, North Carolina was a slave state, in which one-third of the population was enslaved. This was a smaller proportion than in many Southern states. The state did not vote to join the Confederacy until President Abraham Lincoln called on it to invade its sister state, South Carolina, becoming the last or second-to-last state to officially join the Confederacy. The title of "last to join the Confederacy" has been disputed; although Tennessee's informal secession on May 7, 1861, preceded North Carolina's official secession on May 20, the Tennessee legislature did not formally vote to secede until June 8, 1861.