Since 1789, 45 different men have served as President of the United States, and the average age of these men when taking office for the first time was approximately 57 years. Two men, Grover Cleveland and Donald Trump, were elected to two non-consecutive terms, and Donald Trump's victory in 2024 made him the oldest man ever elected as president, where he will be 78 years and seven months old when taking office again. Record holders The oldest president to take office for the first time was Joe Biden in 2021, at 78 years and two months - around five months younger than Donald Trump when he assumes office in 2025. The youngest presidents to take office were Theodore Roosevelt in 1901 (42 years and 322 days), who assumed office following the assassination of William McKinley, and the youngest elected president was John F Kennedy in 1961 (43 years and 236 days). Historically, there seems to be little correlation between age and electability, and the past five presidents have included the two oldest to ever take office, and two of the youngest. Requirements to become president The United States Constitution states that both the President and Vice President must be at least 35 years old when taking office, and must have lived in the United States for at least 14 years of their life. Such restrictions are also in place for members of the U.S. Congress, although the age and residency barriers are lower. Additionally, for the roles of President and Vice President, there is a "natural-born-citizen" clause that was traditionally interpreted to mean candidates must have been born in the U.S. (or were citizens when the Constitution was adopted). However, the clause's ambiguity has led to something of a reinterpretation in the past decades, with most now interpreting it as also applying to those eligible for birthright citizenship, as some recent candidates were born overseas.

Donald Trump's second inauguration, which took place on January 20, 2025, attracted **** million viewers across the United States. Trump's first inauguration in 2017 was watched by significantly more people. Ronald Reagan's first inauguration was the most viewed among all since 1969.

In 2021, President Biden's inaugural address was 2,371 words long. The longest inaugural address was William H. Harrison's in 1841, which amounted to 8,445 words.

Of the forty* men who have been elected to the office of U.S. president, the average weight of U.S. presidents has been approximately 189lbs (86kg). The weight range has been between 122lbs (55kg) and 332lbs (151kg), meaning that the heaviest president, William Howard Taft, was almost three times as heavy as the lightest president, James Madison (who was also the shortest president). Although Taft weighed over 300lbs during his presidency in 1909, he did implement a fitness and dietary regimen in the 1920s, that helped him lose almost 100lbs (45kg) before his death due to cardiovascular disease in 1930. Increase over time The tallest ever president, Abraham Lincoln (who was 6'4"), actually weighed less than the presidential average, and also less than the average adult male in the U.S. in 2018. It is important to note that the average weight of U.S. males has gradually increased in the past two decades, with some studies suggesting that it may have even increased by 15lbs (7kg) since the 1980s. The presidential averages have also increased over time, as the first ten elected presidents had an average weight of 171lbs (78kg), while the average weight of the ten most recent is 194lbs (88kg). Recent presidents In recent years, the heaviest president has been Donald Trump, who weighed 237lbs (108kg) during his first term in office; however medical reports published in June 2020 show that he gained 7lbs (3kg) during this term. There was also controversy in 2018, when it appeared that Trump's official height had been increased from 6'2" to 6'3", which many speculated was done to prevent him from being categorized as "obese" (according to his BMI). In the past half century, George H. W. Bush and Bill Clinton were the only other presidents to have weighed more than the presidential average, although both men were also 6'2" (188cm) tall. President Joe Biden weighs below the presidential average, at 177lbs (81kg).