Certification of the 26th Amendment
The 26th Amendment to the Constitution, lowering the voting age to 18, was certified by General Services Administrator Robert Kunzig on July 1, 1971. In a ceremony at the White House, President Richard M. Nixon, with several 18-year-olds watching, also signed as a witness. He took the unprecedented step of inviting three 18-year-olds to also sign the new amendment.
National Archives, General Records of the U.S. Government