List of presidents of the United States by age
The median age upon accession to the presidency is 55 years and 3 months. This is how old Lyndon B. Johnson was at the time of his inauguration. The youngest person to assume the office was Theodore Roosevelt, who became president at the age of , following William McKinley's assassination; the oldest was Donald Trump, who was old at his inauguration. The youngest person to be elected president was John F. Kennedy, at of age on election day; the oldest was Ronald Reagan, who was old at the time of his election to a second term.
1960 United States presidential election
During the campaign, Kennedy charged that under Eisenhower and the Republicans the nation had fallen behind the Soviet Union in the Cold War, both militarily and economically, and that as president he would "get America moving again." The Eisenhower administration had established NASA in 1958, but Kennedy believed that the Republican Party had ignored the need to catch up to the Soviet Union in the Space Race. He promised that the new Democratic administration would fully appreciate the importance of space accomplishments for the national security and international prestige of the United States. Nixon responded that, if elected, he would continue the "peace and prosperity" that Eisenhower had brought the nation in the 1950s. Nixon also argued that with the nation engaged in the Cold War with the Soviets, that Kennedy was too young and inexperienced to be trusted with the presidency -Nixon was only four years older than Kennedy. Had Nixon been elected, at 48 years, 11 days, he would have been the fourth-youngest president at the date of inauguration. Kennedy, by contrast, was 43 years, 236 days, on the date of his inauguration; the second-youngest man to begin a Presidency (at 42 Theodore Roosevelt, who assumed the Presidency upon the assassination of President William McKinley 60 years previously, was the youngest).