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.
Political career of John C. Breckinridge
The political career of John C. Breckinridge included service in the state government of Kentucky, the Federal government of the United States, as well as the government of the Confederate States of America. In 1857, 36 years old, he was inaugurated as Vice President of the United States under James Buchanan. He remains the youngest person to ever hold the office. Four years later, he ran as the presidential candidate of a dissident group of Southern Democrats, but lost the election to the Republican candidate Abraham Lincoln.