The Thirteenth Amendment to the United States Constitution abolished slavery and involuntary servitude, except as punishment for a crime. It was passed by the U.S. Senate on April 8, 1864. The U.S. House of Representatives passed it on January 31, 1865. The measure was swiftly ratified by all but three Union states (the exceptions were Delaware, New Jersey, and Kentucky), and by a sufficient number of border and "reconstructed" Southern states. It was ratified by December 6, 1865. On December 18, 1865, Secretary of State William H. Seward proclaimed it to have been incorporated into the federal Constitution. It became part of the Constitution 61 years after the Twelfth Amendment. This is the longest interval between constitutional amendments to date.