There’s a transition between memory and history that happens as events stop being personal experiences and start being records. As the generation that experienced a certain era (World War II, the Cuban Missile Crisis, 9/11), begins to disappear from the scene, that era becomes “historical” in a way that it wasn’t before.
So, too, when the remnants of an era begin to disappear:
My name is Ozymandias, king of kings:
Look on my works, ye Mighty, and despair!
Nothing beside remains. Round the decay
Of that colossal wreck, boundless and bare,
The lone and level sands stretch far away.
This process can be fast. My first year students this semester were 10-11 years old when 9/11 happened, and they remember it much less distinctly than I do.
It can be slow. The flagship of Admiral George Dewey’s Asiatic Fleet from the Spanish-American War, the USS Olympia is still open for public viewing on the Philadelphia waterfront. Not for long, though. The Olympia has not been dry-docked since it arrived in Philadelphia in the 1940s and is rotting away in the water:
The waterline is marked with scores of patches, and sections of the mazelike lower hull are so corroded that sunlight shines through. Above deck, water sneaks past the concrete and rubberized surface layers, past the rotting fir deck underneath, and onto the handsomely appointed officers’ quarters below.
The ship is likely to be scrapped in the next year or so, leaving behind only the record of its existence and the history of its achievements.