The President of the United States is the elected head of state and head of government of the United States. The president leads the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces. The president is indirectly elected to a four-year term by the people through the Electoral College.
Since the office was established in 1789, 44 men have served as president. The first, George Washington, won a unanimous vote of the Electoral College. Grover Cleveland served two non-consecutive terms in office, and is counted as the nation's 22nd and 24th presidents; the incumbent, Donald Trump, is therefore the 45th president. There are currently five living former presidents. The most recent death of a former president was on December 26, 2006 with the death of Gerald Ford.
William Henry Harrison's presidency was the shortest in American history. He died 31 days after taking office in 1841. Franklin D. Roosevelt served the longest, over twelve years, before dying early in his fourth term in 1945. He is the only U.S. president to have served more than two terms. Since the ratification of the Twenty-second Amendment to the United States Constitution in 1951, no person may be elected president more than twice, and no one who has served more than two years of a term to which someone else was elected may be elected more than once.
Of the elected presidents, four died in office of natural causes (William Henry Harrison, Zachary Taylor, Warren G. Harding, and Franklin D. Roosevelt), four were assassinated (Abraham Lincoln, James A. Garfield, William McKinley and John F. Kennedy), and one resigned (Richard Nixon). John Tyler was the first vice president to assume the presidency during a presidential term, and set the precedent that a vice president who does so becomes the fully functioning president with his own presidency, as opposed to a caretaker president. The Twenty-fifth Amendment to the Constitution put Tyler's precedent into law in 1967. It also established a mechanism by which a mid-term vacancy in the vice presidency could be filled. Richard Nixon was the first president to fill a vacancy under this Provision when he appointed Gerald Ford to the office. Later, Ford became the second to do so when he appointed Nelson Rockefeller to succeed him. Previously, a mid-term vacancy was left unfilled.