Here’s one I missed. Jimmy Carter’s death means that the sitting president is also the oldest living president. Joe Biden, born in 1942, is older than Bill Clinton, George W. Bush, and Donald Trump (all born in 1946—the only year to see the births of three future presidents) and Barack Obama (born in 1961).

The last time that happened was when Ronald Reagan was president (1981–89). Born in 1911, he was older than Richard Nixon and Gerald Ford (both born in 1913) and Jimmy Carter (1924).

The other times the sitting president was also the oldest were:

All of George Washington’s tenure (1789–97), as the only president.

From December 14, 1799—George Washington’s death—until he left office on March 4, 1801, John Adams was also the only living president.

From June 28, 1836—James Monroe’s death—until he left office on March 4, 1837, Andrew Jackson was both the current and oldest president. His predecessor, John Quincy Adams, was born four months after Jackson in 1767.

From July 31, 1875—Andrew Johnson’s death—until he left office on March 4, 1877, Ulysses Grant was the only living president.

From January 17, 1893—Rutherford Hayes’ death—until he left office on March 4, 1893, Benjamin Harrison was both the current and oldest president (he was three and a half years older than his successor and predecessor, Grover Cleveland).

From June 24, 1908—Grover Cleveland’s death—until he left office on March 4, 1909, Theodore Roosevelt (the youngest ever to become president) was the only living president. Roosevelt’s successor, William Howard Taft, was a year older than Roosevelt, so he was the current and oldest president for his entire term, 1909–13. Woodrow Wilson was nine months older than Taft, so he was the current and oldest president for his entire term, 1913–21.

From January 5, 1933—Calvin Coolidge’s death—until he left office on March 4 of that year, Herbert Hoover was the only living president.

From January 22, 1973—Lyndon Johnson’s death—until he resigned in August of that year, Richard Nixon was the only living president.