The 25th Amendment of the United States Constitution is ratified.

Twenty-fifth Amendment, amendment (1967) to the Constitution of the United States that set forth succession rules relating to vacancies and disabilities of the office of the president and of the vice president. It was proposed by the U.S. Congress on July 6, 1965, and it was ratified on Feb. 10, 1967. While the first section of the Twenty-fifth Amendment codified the traditionally observed process of succession in the event of the death of the president—that the vice president would succeed to the office—it also introduced a change regarding the ascent of the vice president to president should the latter resign from office. In the event of resignation, the vice president would assume the title and position of president—not acting president—effectively prohibiting the departing president from returning to office.

Prior to the passage of the amendment, nine presidents—William Henry Harrison, Zachary Taylor, Abraham Lincoln, James Garfield, William McKinley, Woodrow Wilson, Warren G. Harding, Franklin D. Roosevelt, and Dwight D. Eisenhower—experienced health crises that left them temporarily incapacitated, with death resulting in six cases. After the passage of the amendment, Pres. Ronald Reagan was incapacitated for some 24 hours while undergoing surgery for a gunshot wound resulting from a failed assassination attempt, though no official designation of presidential responsibility was ever made. Indeed, this portion of the Twenty-fifth Amendment has never been invoked.