Although the term was coined at the 1939 New York World’s Fair, time capsules date back to the Gilded Age and Progressive Era, when autographs, photographs, and other artifacts were sealed in various cities as tributes to the bourgeois elite. These memorial safes and chests, while related to cornerstone deposits, were inspired by new concerns about the proliferation and decay of paper records, the inadequacy of monuments, and the specter of class apocalypse. But amid mounting labor unrest, they proved contentious, provoking widespread criticism and inspiring fictional reappropriations by authors including Mark Twain and the socialist George Allan England.