While the United States' 16th president, Abraham Lincoln, was key in pushing through the 13th Amendment that abolished slavery, it seems that the film "Lincoln" has called attention to an error in Mississippi law: the state never actually ratified the slavery-outlawing amendment.
University of Mississippi neurobiology professor Ranjan Batra checked the state law after seeing Spielberg's film, and discoverd the clerical mistake. With the help of UMC anatomical materialist specialist Ken Sullivan, the two worked together to make the ratification official. Sullivan, a long-time Mississippi resident, remembered that a move to ratify the 13th amendment had passed in the State Senate and House in 1995. After tracking down a copy of the bill he discovered the last paragraph required the document to be sent to the office of federal registry for an official signature. This never happened.
Batra and Sullivan brought this to government attention, and the bill was subsequently completed by Mississippi's Secretary of State, Delbert Hoseman, who contacted the director of the Federal Register, Charles A. Barth.
The abolition of slavery was officially noted in the Constitution on December 6, 1865, making Mississippi's completed ratification on February 7, 2013, 147 years late -- better than never.