Countdowns serve many purposes. The New Year’s Eve countdown might be characterized as a “genesis countdown” — after time runs out, it starts over again. The wait for the new year — with its predictions and parties — is typically generative and hopeful. But there are also “apocalyptic countdowns,” in which after time runs out, disaster ensues.

Both of these countdown types took form during the Atomic Age.

In 1947, the Bulletin of the Atomic Scientists introduced the Doomsday Clock, which to this day provides a visual reckoning of our proximity to apocalypse. These same scientists also used “count down” in atomic bomb tests. A 1953 San Francisco Examiner article reported on a Nevada test: “A designated official on a loudspeaker and short-wave radio hookup announces at intervals the time remaining before the explosion. At the very end he intones ‘minus 10 seconds, minus 5 seconds and minus 4 seconds’ and so on down to the moment of the explosion.”

In 1957, Alfred Hitchcock domesticated the atomic countdown in the “Four O’Clock” episode of the television series “Suspicion,” transplanting it into a suburban basement wired with explosives in the seconds before the eponymous time. On May 5, 1961, the countdown got its first major positive association when some 45 million Americans heard the countdown to the successful launch of America’s first manned space flight, with astronaut Alan Shepard saying, “Roger, liftoff and the clock has started.”

The countdown associated with rocket launches had its origins in the Weimar Republic, where Fritz Lang’s 1929 film “Woman in the Moon” featured an extended countdown to a moon rocket launch. The science fiction multi-reel film had an outsized impact on Germany’s rocket scientists, who after World War II became central to the American space program.

During the 1970s, the countdown moved onto radio and television shows. By counting down to the latest greatest song, these shows slowed the rush of time and demarcated the recent past. Their terrain was not time, but rather “the top” or “the most popular,” leading not to “zero” but to “number one.”

All these countdowns eventually made way for the New Year’s countdown.  Americans began celebrating New Year’s Eve publicly in the 1890s, including with the ringing of bells (mostly at churches) at midnight. But the first countdown I identified was in 1957, when broadcaster Ben Grauer proclaimed to a national radio audience from a perch overlooking Times Square, “’58 is on its way, 5-4-3-2-1. The ball is starting to slide down the pole, and it is the signal that ’58 is here.”

He didn’t get much traction: The extant recording features a crowd making merry but definitely not counting down. But Grauer didn’t give up; he kept trying countdown through the 1960s. Dick Clark’s New Year’s Rockin’ Eve, which debuted in the 1970s to welcome, featured confected countdowns staged on its dance party set.

But my research shows that it was not until seconds before the arrival of 1979 that a Times Square crowd counted down to the new year. By the end of the 1980s, countdown clocks were installed in Times Square, and television graphics showed the time remaining until midnight.

The first two decades of the 21st century have careened between genesis and apocalyptic countdowns, from the countdown clocks to Olympic Games to the Climate Clock, found online (and in New York City’s Union Square). Clocks are now ubiquitous; social media clocks count down to your birthday, and transit station screens count down to the arrival of your bus or train.

I suspect that some countdowns, as 2021 gives way to 2022, will be inflected with a tinge of hesitancy and doubt. Still, many of us will want to join in the hopefulness of the genesis count, rejoicing when the new year arrives and the clock starts again.

Alexis McCrossen is a Southern Methodist University historian who studies timekeeping. She wrote this piece for Zócalo Public Square.