William Oughtred, as well as others, developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. Slide rules became increasingly popular in the 1950s and 1960s, before beginning to fall out of favor to pocket calculators, which, by the mid 1970s, had become affordable and were considered significantly easier to use by the masses. The last slide rule manufactured in the United States was produced on July 11, 1976.

Although some overseas companies continue to make slide rules and retailers like ThinkGeek offer replica models, these are often sold for nostalgia or are far more advanced than actual slide rules, some including electronics.

Keuffel & Esser (K&E) Corporation had the honor of producing the last slide rule. The company presented it to the Smithsonian.

Despite the end of slide rule manufacturing, many such tools can be found on engineers’ benches and in their cubes today, decades after the end of production.

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Editor’s note: This article was originally posted on July 11, 2012 and edited on July 11, 2019.