When reminiscing, a popular mnemonic device is to recount where you were at the time a major personal, national or global event took place, such as the election and inauguration of a new president.

The United States has had only 45 such figures. In contemporary times, the increasing likelihood of reelection means an actual new president taking power is a rare occasion. For reference, my grandpa is 78: He’s been alive for nearly one-third of our country’s existence, yet President Trump is just the 14th different president he’s lived under.