American presidents have varied in age at the time of taking office, but most have been in their 50s when inaugurated. Here are some key facts about the ages of U.S. presidents:
  1. The median age for U.S. presidents at their first inauguration is 55 years old[5].
  2. Joe Biden is currently the oldest president to take office, having been inaugurated at 78 years and 61 days old[1][3].
  3. The youngest elected president was John F. Kennedy, who took office at 43 years and 236 days old[3].
  4. Theodore Roosevelt became the youngest president overall at 42 years and 322 days old when he succeeded William McKinley after his assassination[3].
  5. Most presidential inaugurations (35 out of 68) have involved presidents in their 50s[5].
  6. The age range for presidents at inauguration has spanned from 42 to 78 years old[3].
  7. After Biden, the second-oldest president at inauguration was Donald Trump at 70 years and 220 days[3].
  8. Ronald Reagan was 69 years and 348 days old when he took office, making him the oldest president before Trump and Biden[3].
  9. On average, presidents are sworn in at 55 years old[3].
  10. For re-elected presidents serving a second term, the median age at second inauguration is 58 years old[5].
It's worth noting that life expectancy in the United States has increased considerably over time, which may influence the age at which recent presidents have taken office compared to earlier periods in American history[5].