It doesn’t seem possible, but Mississippi never ratified the 13th Amendment. Until now.
Life really does move slower in the South. One hundred forty-eight years after Congress sent the 13th Amendment outlawing slavery to the states for ratification, Mississippi officially has joined the ranks. The state’s Legislature did vote to ratify it in 1995 — but the vote was never made official because lawmakers failed to inform the U.S. archivist, according to a report in the Clarion-Ledger. They’ve finally finished the job, Newser reports, and it’s official: Slavery is unconstitutional in Mississippi.
According to Wikipedia, Kentucky only ratified the amendment in 1976.