How do we construct a genealogy or effective history of the countdown of time? Such countdowns involve both telling time and counting time, marked off in pre-determined increments to a pre-determined end. Countdowns both spectacular and mundane have become a routine part of contemporary life in the United States. At New York City's Times Square, for example, hundreds of thousands (recently, millions) of people gather in front of a giant countdown clock every 31 December to count off the final ten seconds of the old year and welcome a new year. In sports such as football and basketball, a countdown clock is used not merely to tell the amount of time remaining until the end of the game but also to divide the game into timed segments, between which a television commercial may be inserted or an instant replay staged to settle a dispute over a particular referee ruling. The music industry also commonly uses a countdown in its Top Forty playlists and rankings of popular songs or music videos. In downtown Columbus, Ohio, in the year 2000, I saw a countdown clock used at a construction site to tell the public the remaining seconds before the completion of the building.

Public countdowns also take place in other countries, as in China, where a giant multimedia countdown clock was set up at Beijing's Tiananmen Square to count down to Hong Kong's ‘return’ to China on 1 July, 1997.