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.
Theodore Roosevelt
After taking office as Vice President in March 1901, he became President at age 42 following McKinley's assassination that September, and remains the youngest person to become President of the United States. As a leader of the Progressive movement, he championed his "Square Deal" domestic policies, promising the average citizen fairness, breaking of trusts, regulation of railroads, and pure food and drugs. Making conservation a top priority, he established many new national parks, forests, and monuments intended to preserve the nation's natural resources. In foreign policy, he focused on Central America, where he began construction of the Panama Canal. He expanded the Navy and sent the Great White Fleet on a world tour to project the United States' naval power around the globe. His successful efforts to broker the end of the Russo-Japanese War won him the 1906 Nobel Peace Prize. He avoided controversial tariff and money issues. Elected in 1904 to a full term, Roosevelt continued to promote progressive policies, many of which were passed in Congress. Roosevelt successfully groomed his close friend, William Howard Taft, and Taft won the 1908 presidential election to succeed him.