who was the youngest us president to die in office
List of presidents of the United States by age Assassinated three years into his term, John F. Kennedy was the youngest at the time of leaving office (46 years, 177 days); the youngest president to leave office at the conclusion of a normal transition was Theodore Roosevelt (50 years, 128 days). The oldest at the time of leaving office was Ronald Reagan (77 years, 349 days).