The United States has had 45 presidents, as of 2018. This number includes the presidents sworn into office after the ratification of the United States Constitution in 1789.
Although the number of presidents counts as 45, the actual number of people who have served as president is 44. This is because Grover Cleveland was elected into office for two nonconsecutive terms and counts as both the 22nd and the 24th president. Out of the 44 presidents, four have died in office, four have been assassinated and one has resigned. Franklin D. Roosevelt is the only president to serve for more than two terms in office. William Henry Harrison, who spent 32 days in office, has so far served the shortest time.