William Mckkinley, the 25th US President

This picture preserves a moment few cameras ever caught — William MckKinley, The 25th US President, Walking Into The Expo Where He Would Be Shot Twice And K**led. Like the best archival images, it needs almost no explanation — the frame tells its own story.

Photography has only existed since 1839, which means the camera-recorded past is a narrow window — and every surviving frame from it is a small act of preservation, whether the photographer knew it or not.

Moments like this one were captured by photographers who often had a single chance to get the shot — no second takes, no digital preview. That is part of why these frames carry such weight: each one is a split second of real history, fixed for good.