The Washington Post recently pointed out that America’s 238 years of existence can be summed up in the overlapping lives of just four United States presidents. It works like this: When President Obama was born in 1961, President Herbert Hoover was still alive (1874-1964). When Hoover was born, America’s 17th president, President Andrew Johnson, was still alive (1808-1875). And when Andrew Johnson was born, the extraordinarily long-lived President John Adams was still alive (1735-1826). The article was inspired by a reddit discussion about famous historical figures whose lives overlapped.