When Donald Trump was inaugurated in January 2017, he became the oldest commander-in-chief sworn in at the age of 70 years and 220 days old.
That was surpassed by his successor Joe Biden, who was 78 years and 61 days when he became the country’s 46th president in January 2021.
Before Mr Trump, Ronald Reagan was the oldest person to assume the presidency at 69 years and 349 years old at his first inauguration in 1981.
Reagan was the oldest president when he left office at the age of 77 in 1989, just 22 days away from turning 78.
But depending on who wins the 2024 presidential election, a new record could be set as both Mr Biden and Mr Trump are running for reelection.
If Mr Biden were to win reelection he would be 81 years old on election day, 15 days away from his 82nd birthday. Mr Trump would be 77.
The average life expectancy of an American male if they first reach the age of 60, is 75.6 years.
2024 will be the first election where both candidates are older than the national average life expectancy, according to This Interests Me.
During the 2020 election campaign, both men faced questions about their health, with Mr Trump’s aides giving evasive answers after he was hospitalised with Covid.
Observers have pointed out that Mr Trump, a fan of fast food, is medically obese, has refused to lose weight, takes cholesterol management drugs and was treated with a string of experimental drugs during his bout with Covid.
Meanwhile, Mr Trump and right-wing media outlets tried to portray Mr Biden as a confused and elderly man unfit for office.
At the other end of the scale, Democrat John F Kennedy became the youngest ever US president at the age of 43 when he was inaugurated in 1961.
Kennedy announced his candidacy for president at the age of 42 before beating Richard Nixon in the 1960 election.
The youngest president to assume office was Theodore Roosevelt, who took office in September 1901 at the age of 42 following the assassination of William McKinley.
The average age of a US president, when sworn in, is 55.