The youngest person to become U.S. president was Theodore Roosevelt, who assumed office at the age of 42 years and 322 days after the assassination of President William McKinley in 1901
. However, Roosevelt was not elected initially; he succeeded to the presidency. The youngest president to be elected was John F. Kennedy, who was inaugurated at age 43 years and 236 days in 1961
. In summary:
- Youngest president ever (by succession): Theodore Roosevelt at 42 years old.
- Youngest president elected: John F. Kennedy at 43 years old.
