After Abraham Lincoln was elected President of the United States in November 1860, the South Carolina State Legislature called for elections to a state convention to be held on December 17th.  On December 20th, all 169 delegates to the convention voted for secession against Republican Presidential leadership on matters of race, economics, and politics.  This document states that South Carolina has repealed the Constitution and its amendments and disassociated itself from the United States of America.

http://avalon.law.yale.edu/19th_century/csa_scarsec.asp