the youngest president of usa
The average age of accession is 54 years and 11 months, which falls between Herbert Hoover (22nd) and Lyndon B. Johnson (23rd). The youngest person to assume office was Theodore Roosevelt (age 42), who became president following William McKinley 's assassination.he oldest president to assume office was Ronald Reagan (age 69 years, 349 days), who was also the oldest in office (age 77 years, 349 days), ending at the inauguration of George H. W. Bush. The oldest living president is George H. W. Bush, born June 12, 1924 (aged 7009288306000000000â  91 years, 131 days).