The United States has had 43 presidents since George Washington came to office April 30, 1789. The number of presidencies as of the first half of 2013 numbered 44 because Grover Cleveland served two nonconsecutive terms in office.
List of all U.S. presidents
Some presidential facts
Only one person—Franklin D. Roosevelt—has ever served more than two terms. FDR was elected to four consecutive terms but died less than two months into his final term. The three other presidents who died of natural cause while in office are William Henry Harrison, Zachary Taylor and Warren G. Harding. Four sitting presidents have been assassinated: Abraham Lincoln, James A. Garfield, William McKinley and John F. Kennedy.
When the president of the United States dies, is impeached, or resigns from office, the vice president becomes president for the remainder of the term. This has occurred nine times in the country's history, with the last instance being the resignation of Richard Nixon in 1977.
Gerald R. Ford, who succeeded Nixon, is the only person to have ever served as president without being elected even to the vice presidency, as he was appointed to that office according to the terms of the 25th Amendment when Spiro Agnew resigned due to criminal charges. Four elected vice presidents who finished out a presidential term—John Tyler, Millard Fillmore, Andrew Johnson and Chester A. Arthur—were never elected as president.