The President of the United States is the chief executive of the United States. The office was introduced by the US Constitution, adopted by the Constitutional Convention (Assembly) in 1787. George Washington became the first president of the United States in 1789. Prior to his inauguration, the name “president” was used in conjunction with “President of the Continental Congress” – the chairman of the convention of representatives of the colonies, which adopted the Declaration of Independence.
US presidents have been elected since 1789. Consecutive terms are traditionally numbered as one presidency (for example, George Washington, who was elected twice in a row, was the first president, not the first and second), and the only current interruption in office (Grover Cleveland) is counted as two presidencies (22nd and 24th president). Vice-presidents who take over as president in the event of his death or resignation receive a separate number.
Eight American presidents have died while in office. Four died during the exercise of their powers from natural causes (William Henry Garrison, Zachary Taylor, Warren Harding and Franklin D. Roosevelt), four presidents were assassinated: Lincoln (1865, a southerner in the theater), Garfield (1881, train station insane), McKinley (1901, anarchist on display) and Kennedy (1963, Lee Harvey Oswald), and one resigned (Richard Nixon).
During the Civil War from 1861 to 1865, there was a presidency of the Confederate States of America when the southern states declared themselves independent and seceded from the United States. The first and only president of the CSA was Jefferson Davis, who held this post from 18 February 1861 to 10 May 1865 (Alexander Stevens was vice president at that time).