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.
William Henry Harrison
Harrison returned to private life in Ohio until 1836, when he was nominated for the presidency as the Whig Party candidate in the election of that year; he was defeated by Democratic Vice President Martin Van Buren. In 1840, the Party nominated Harrison again, with John Tyler as his running mate. Harrison and Tyler, known famously as "Tippecanoe and Tyler Too", defeated Van Buren in the 1840 election. Harrison was the oldest person to be elected president until Ronald Reagan in 1980 and later Donald Trump in 2016. Harrison died of pneumonia a month after taking office, and Tyler assumed the presidency, setting a major precedent in succession. Due to Harrison's brief time in office, scholars and historians often forgo listing this president in historical rankings.