1947 – U.S. President Truman signed the Presidential Succession Act, which placed the Speaker of the House and the Senate President Pro Tempore next in the line of succession after the vice president.


President Harry Truman signed an Executive Order determining the line of succession if the president becomes incapacitated or dies in office. Following the vice president, the speaker of the house and president of the Senate are next in succession. This became the 25th Amendment to the U.S. Constitution, ratified on February 10, 1967.