The Last State to Ratify the 13th Amendment

Mississippi was the last U.S. state to officially ratify the 13th Amendment abolishing slavery, and the delay was extraordinary even by the standards of Reconstruction-era politics. Mississippi legislators voted to ratify in 1995, 130 years after the amendment was adopted, but due to a clerical error in which the paperwork was never filed with the Office of the Federal Register, the ratification was not officially recorded until February 7, 2013. The error was discovered by a doctor who had watched the film Lincoln and decided to look into the historical record.

Source: ABC News