The office of the US president was established in 1789, and in the 231 years since the first man was elected to the highest office in the country, 44 have people have held the title.
US Presidents are only allowed to sit for a maximum of two, four year terms, but although any gender can hold the position, every president so far has been a man.
Of the 44 who have held office, only ten presidents have failed to win re-election for a second term, when they have attempted to.
One US president, John F Kennedy was assassinated before he could run for re-election.
The longest period the US has experienced without a president failing to complete two terms, was between 1932 and 1976.
How US Presidents have aged during their time in office
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1/16How US Presidents have aged during their time in office
How US Presidents have aged during their time in office
Barack Obama holds his 2015 end of year press conference at the White House
Reuters
How US Presidents have aged during their time in office
Obama takes the oath of office on his Inauguration Day in January 2009
Reuters
How US Presidents have aged during their time in office
George W Bush makes a phone call shortly after the 2000 election
Reuters
How US Presidents have aged during their time in office
Bush fields questions during his final White House press briefing on January 12, 2009
Reuters
How US Presidents have aged during their time in office
Hillary Clinton whispers to then-President-elect Bill Clinton at a dinner several days before his first inauguration in 1993
Reuters
How US Presidents have aged during their time in office
Clinton gives a brief speech toward the end of his term in October 2000
Reuters
How US Presidents have aged during their time in office
Appearing without his trademark glasses, then-Vice President George H W Bush answers a question at the second presidential debate in October 1988
AP
How US Presidents have aged during their time in office
Bush addresses a crowd of veterans during a ceremony at the Korean War Memorial in June 1992, several months before losing the presidential election
AP
How US Presidents have aged during their time in office
Former President Ronald Reagan and first lady Nancy Reagan greet fans lined up in Washington at his first inauguration in January 1981
AP
How US Presidents have aged during their time in office
Reagan returns to Washington after his final trip as president to Camp David in January 1989
AP
How US Presidents have aged during their time in office
Jimmy Carter emerges from a Georgia voting booth on Election Day in November 1976
AP
How US Presidents have aged during their time in office
A photographer captures Carter preparing for his farewell address to the nation in January 1981
AP
How US Presidents have aged during their time in office
President Richard Nixon gives a press conference in the East Room of the White House several weeks after being sworn in in 1969
AP
How US Presidents have aged during their time in office
In this photo, a glassy-eyed Nixon delivers a final speech for White House staff and members of his cabinet
AP
How US Presidents have aged during their time in office
President Lyndon Johnson proclaims a day of mourning for deceased President John F. Kennedy shortly after being sworn in
AP
How US Presidents have aged during their time in office
Johnson, who didn’t visibly age too much in his five-year tenure, joins Nixon shortly after Nixon is elected president in November 1968
AP
The last president to have failed to win re-election was George H W Bush, who lost to Bill Clinton in 1992.
The US has gone 28 years without a president failing to win a second term, and in November, president Donald Trump will face Joe Biden in the presidential election, with the former attempting to win re-election.
Find out about the presidents who failed to win re-election, below.
Follow live: US election results 2020
The first US president to fail to win re-election for a second term, was John Adams, who also served as the countrys first vice president.
When the position was created in 1789, George Washington was the first to have the honour, and Mr Adams served under him.
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After Mr Washington completed his two terms, Mr Adams ran for the position with the Federalist party and took his place as president.
During his time as president, Mr Adams engaged in a quasi-war with France after they captured a merchant vessel in New York City harbour.
He came third in the next election, behind the two candidates the Republican party ran, with Thomas Jefferson eventually becoming the new US president.
Another of the Adams family, John Quincy Adams, was unable to win re-election for a second term as US president.
Mr Adams was the eldest son of the second US president, and was the sixth man to hold the position.
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During his time as president, there were big rifts in his party, the Democratic-Republican party, and it stopped him from making much progress.
The party split after Mr Adams failed to win re-election, with the two sides becoming the Democratic party and the Whig party.
Mr Adams became the second US president to fail to win a second term, meaning that at the time the two Adams were the only presidents to have failed to win re-election.
Grover Cleveland and Benjamin Harrison
Martin Van Buren was the next president to fail to win re-election in 1840, but Grover Cleveland proved that a lost election does not stop you from getting your second term.
Mr Cleveland, a Democrat, was the 22nd and the 24th president of the United States, after he won both the 1884 and 1892 elections.
He won the popular vote in 1888, but lost the election to the Republican Benjamin Harrison, who served for the next four years.
The 1888 election was tight and in 1892, Mr Cleveland defeated Mr Harrison, to win back the presidency and cause Mr Harrison to become the fifth president to fail to win re-election.
William Howard Taft was the next US president to fail to win re-election, 20 years later in 1912.
Mr Taft, a Republican, is the only person in US history to have held both the position of president and chief justice of the United States.
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As president, Mr Taft said he would not appoint African Americans to federal jobs and removed a majority of Black office holders in the south.
He is considered by most historians as an average president, as his four years in charge were unremarkable.
He served as president from 1909 to 1913 and lost the 1912 presidential election to Woodrow Wilson.
Herbert Hoover was elected as US president in 1928, and was faced with helping the country rebuild after the stock market crash of 1929.
As president, Mr Hoover oversaw congress voting to repeal prohibition, despite pushing to make sure alcohol remained illegal in the US.
His presidency was overshadowed by the economic crash in 1929, and he spent most of his one term attempting to improve the countrys economy.
The US had not recovered by the time of the 1932 election, and he lost to Franklin D Roosevelt.
Gerald Ford and Jimmy Carter
Gerald Ford not only failed to win re-election as the US president, but also never won a presidential election.
Mr Ford, a Republican, became the president after Richard Nixon resigned, following the Watergate scandal.
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He served from 1974 to 1977, when Jimmy Carter defeated him in the 1976 election.
Mr Carter, a Democrat served as the US president from 1977 to 1981, but lost the 1980 election to Ronald Reagan.
Despite the fact Gerald Ford never won a presidential election, Mr Carters loss, meant that for the first time, two US presidents in succession failed to win re-election.
George H W Bush was the last president to fail to win re-election, when he was beaten by Democrat, Bill Clinton, in the 1992 election.
Mr Bush was the 41st US president and was the director of the CIA from 1976 to 1980.
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He served as Mr Reagans vice president from 1981 until 1989, when he was elected to take his position.
As president, Mr Bush engaged in the Gulf War and signed the Americans with Disabilities act 1990 into law.
In 2000, his son, George W Bush was elected as president and completed two full terms, before Barack Obama took over as US president.
