thumb|300px|The White House, the president's official residence and place of business
Under the U.S. Constitution, the President of the United States is the head of state and the head of government of the United States. As chief of the executive branch and head of the federal government as a whole, the presidency is the highest political office in the United States by influence and recognition. The president is also the Commander-in-Chief of the U.S. armed forces. The president is indirectly elected to a four-year term by an Electoral College (or by the House of Representatives should the Electoral College fail to award an absolute majority of votes to any person). Since the ratification of the Twenty-second Amendment to the United States Constitution in 1951, no person may be elected to the office of the president more than twice. Upon death, resignation, or removal from office of an incumbent president, the Vice President assumes the office. This list includes only those persons who were sworn into office as president following the ratification of the United States Constitution, which took effect on March 4, 1789. For American leaders before this ratification, see President of the Continental Congress. The list does not include any Acting Presidents under the Twenty-fifth Amendment to the United States Constitution.

There have been forty-three people sworn into office, and forty-four presidencies, due to the fact that Grover Cleveland served two non-consecutive terms and is counted chronologically as both the twenty-second and the twenty-fourth president. Of the individuals elected as president, four died in office of natural causes (William Henry Harrison, Zachary Taylor, Warren G. Harding, and Franklin D. Roosevelt), one resigned (Richard Nixon), and four were assassinated (Abraham Lincoln, James A. Garfield, William McKinley, and John F. Kennedy). The first president was George Washington, who was inaugurated in 1789 after a unanimous Electoral College vote. William Henry Harrison spent the shortest time in office at 31 days in 1841. At over twelve years, Franklin D. Roosevelt spent the longest time in office, and is the only president to serve more than two terms, but he died shortly into his fourth term in 1945. The current president is Barack Obama; he assumed the office on January 20, 2009.

Presidents

Parties