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.
John C. Breckinridge
John Cabell Breckinridge (January 16, 1821 – May 17, 1875) was an American lawyer, politician, and soldier. He represented Kentucky in both houses of Congress and became the 14th and youngest-ever vice president of the United States, serving from 1857 to 1861. He was a member of the Democratic party. He served in the U.S. Senate during the outbreak of the American Civil War, but was expelled after joining the Confederate Army. He was appointed Confederate secretary of war in 1865.