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.
Nellie Grant
Nellie Grant (July 4, 1855 – August 30, 1922) was the third child and only daughter of U.S. President Ulysses S. Grant and First Lady Julia Grant. At the age of 16, Nellie was sent abroad to England by President Grant, and was received by Queen Victoria. She was also regarded, popularly, by girls, as a teenager growing up in the White House and so attracted much attention.