Americans naturally tend to think of their presidents, like their families, in terms of generations. This may have started with the news that John Adams and Thomas Jefferson had both died on July 4, 1826, half a century to the day from the time the Continental Congress adopted the Declaration of Independence they jointly drafted.

The Founding Generation (born 1732-1767) held the presidency for nearly half a century, from 1789 to 1837. Five of those presidents were adults during the American Revolution; two had childhood memories of it: John Quincy Adams, who watched gunfire smoke from Bunker Hill at age 7, and Andrew Jackson, who was slashed by a British officer’s sword at age 14.