U.S. survey foot

When the United States adopted the international yard in 1 July 1959¹, the U.S. Coast and Geodetic Survey, mappers of the nation, objected that converting all their geodetic data to international feet would be a horrendous undertaking (remember, this was pre-computer). They were authorized to continue to use the previous definition of the foot, that of the Mendenhall order (U.S. Coast and Geodetic Survey Bulletin 26, April 5, 1893), one foot = ¹²⁰⁰⁄₃₉₃₇ meter. This foot was then denominated the U.S. survey foot, = 1.000 002 international feet. It was used only for land measurements.

By 1986, the mapping service had completed converting the national geodetic grid to international feet.

On 17 October 2019, NIST and other relevant agencies announced plans² to deprecate the U.S. survey foot on 31 December 2022. At the same time, the term “international foot” will be phased out, replaced by “foot”, with the same meaning.

1. 24 FR 5348. Available as a pdf file by searching at federalregister.gov.

2. 84 FR 55562
Invitation for public comment

resources

NIST's PML announcement of the intention to deprecate. It includes valuable links to other pages on the topic, including a video, by themselves and other agencies.PML

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