When Donald Trump is inaugurated in exactly two weeks' time, he'll become the oldest elected president in U.S. history. The average age of all 44 U.S. presidents who have taken office is just over 55 while Trump is 70. Up until now, Ronald Reagan held the title as the nation's oldest president. He was 69 years old when he was sworn into office in 1981.

George H.W. Bush was also older than average when he took office at 64 and interestingly, he holds a notable record among America's former presidents. Today marks his 72nd wedding anniversary to his wife Barbara, making them the longest-married couple in U.S. presidential history.

At the opposite end of the age scale, Theodore Roosevelt became the youngest U.S. president in history following President McKinley's assassination in 1901. Roosevelt was 42 when he took office. John F. Kennedy was slightly older when he got to the White House 60 years later at 43 years of age.