Mississippi officially ratified the 13th Amendment, the amendment to end slavery, on Feb. 7, according to the Clarion-Ledger in Jackson, MS.

The state voted to ratify the amendment in 1995, receiving unanimous support in both the Mississippi Senate and House. However, the secretary of state never sent a copy of the resolution to the Office of the Federal Register. Dick Molpus, then secretary of state, blamed the failure to finalize the resolution on an error in filing.

Dr. Ranjan Batra, an associate professor at the University of Mississippi Medical Center, researched the oversight after watching the film “Lincoln.” He then notified his colleague Ken Sullivan about Mississippi’s failure to ratify the amendment.

Sullivan contacted the office of the Secretary of State Delbert Hosemann, who sent a copy of the 1995 resolution to the Office of the Federal Register. On Feb. 7, the Federal Register notified the state that the office had received the resolution.