Who was the youngest president?

Theodore Roosevelt was the youngest president of the United States at age 42. Roosevelt was serving as vice president when President William McKinley was assassinated, and Roosevelt assumed the office. As the 26th president, he was known for his youthful vigor.

John F. Kennedy was the youngest man to be elected president. He was 43 years old. Following Kennedy in the list of youngest presidents are: Bill Clinton at 46 years, 5 months; Ulysses S. Grant at 46 years, 10 months; Barack Obama at 47 years, 5 months; and Grover Cleveland at 47 years, 11 months. The oldest man elected president was Ronald Reagan, who was 69 years old.