U.S. Survey Foot

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href="/web/20231128173251/https://www.nist.gov/pml">Physical Measurement Laboratory</a> </div> <div class="nist-section-header__sub"> <div class="nist-section-header__main grid-container"> <div class="grid-row"> <div class="nist-section-header__title"> <h1 class="nist-page__title">U.S. Survey Foot</h1> </div> </div> </div> </div> </div> <div class="grid-container margin-top-4"> <div class="grid-row grid-gap-6"> <aside class="nist-page__region nist-page__region--sidebar-first tablet-lg:grid-col-4 desktop-lg:grid-col-3"> <div>  <div data-elastic-exclude="" class="nist-block"> <nav> <ul class="usa-sidenav usa-accordion "> <li class="usa-sidenav__item usa-sidenav__item--parent"> <a href="/web/20231128173251/https://www.nist.gov/pml/us-surveyfoot/frn-citations" data-drupal-link-system-path="">FRN Citations</a> <button class="usa-accordion__button" aria-expanded="false" aria-controls="menu-us-survey-foot-1"><span class="usa-sr-only">Expand or Collapse</span></button> <ul id="menu-us-survey-foot-1" class="usa-sidenav__sublist usa-accordion"> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20231128173251/https://www.federalregister.gov/documents/2020/10/05/2020-21902/deprecation-of-the-united-states-us-survey-foot" data-drupal-link-system-path="">FR DOC 2020 FR 21902 (Published October 5, 2020)</a> </li> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20231128173251/https://www.federalregister.gov/documents/2020/07/10/2020-14882/deprecation-of-the-united-states-us-survey-foot" data-drupal-link-system-path="">FR Doc 2020 FR 14882 (Published July 10, 2020)</a> </li> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20231128173251/https://www.federalregister.gov/documents/2019/10/17/2019-22414/deprecation-of-the-united-states-us-survey-foot" data-drupal-link-system-path="">FR Doc 2019 FR 22414 (Published October 17, 2019)</a> </li> </ul> </li> <li class="usa-sidenav__item"> <a 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paragraph--type--text paragraph--view-mode--default"> <div class="nist-block text-long"><h2 class="nist-block__title">Putting the Best “Foot” Forward: Ending the Era of the U.S. Survey Foot (1959 to 2022)</h2> <figure class="align-right nist-image--lightbox nist-image" data-lightbox="https://www.nist.gov/sites/default/files/styles/2800_x_2800_limit/public/images/2023/01/04/us-survey-foot-obsolete.png?itok=dj4HbnqI" data-media-id="660901"><img alt="U.S. Survey Foot is obsolete" height="480" loading="lazy" src="/web/20231128173251im_/https://www.nist.gov/sites/default/files/styles/480_x_480_limit/public/images/2023/01/04/us-survey-foot-obsolete.png?itok=74PjElQF" typeof="foaf:Image" width="480"/><figcaption class="nist-image__caption"><div class="nist-image__caption-content" data-caption-editable="true"> The U.S. survey foot is obsolete. Only use for historical and legacy applications. </div> <div class="nist-image__credit"> <span class="nist-image__credit-label">Credit:</span> NIST </div> </figcaption></figure><p>Beginning on January 1, 2023, the U.S. survey foot should be avoided, except for historic and legacy applications and has been superseded by the international foot definition (i.e., 1 foot = 0.3048 meter exactly) in all applications. Prior to this date, except for the mile and square mile, the cable’s length, chain, fathom, furlong, league, link, rod, pole, perch, acre, and acre-foot were previously only defined in terms of the U.S. survey foot. With this update, <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="7e41b7bc-1612-469d-87cc-8c1ff2477e6b" href="/web/20231128173251/https://www.nist.gov/pml/us-surveyfoot/revised-unit-conversion-factors" title="U.S. Survey Foot: Revised Unit Conversion Factors">relationships</a> are available in terms of the international foot, which can simply be referred as the “foot.” Either the term “foot” or “international foot” may be used, as required for clarity in technical applications. This is particularly the case for surveying and mapping applications, although over time “foot” will become more prevalent. The preferred measurement unit of length in the United States is the meter (m) and surveyors, map makers, and engineers are encouraged to adopt the SI for their work.</p> <p>Since 1893, the legal definition of the foot in the United States has been based on the meter. The definition adopted at that time was the one specified by Congress in 1866, as 1 foot = 1200/3937 meter <em>exactly</em> (or 1 foot = 0.304 800 6 meter <em>approximately</em>). In 1959, the relationship of the foot to the meter was officially refined as 1 foot = 0.304 8 meter <em>exactly</em>. This change was made to support United States industry and international trade. It resolved a long-standing discrepancy with the definition used by different organizations within the United States and in other countries.</p> <p>The 1959 redefinition of the foot was legally binding and intended for the entire United States. But a single exception <em>temporarily</em> allowed continued use of the previous definition of the foot, exclusively for geodetic surveying. To distinguish between these two versions of the foot, the new one was named the “international foot” and the old one the “U.S. survey foot.” It was furthermore <em>mandated</em> that the U.S. survey foot be replaced by the international foot upon readjustment of the geodetic control networks of the United States. Although such a readjustment was completed in 1986, use of the U.S. survey foot persisted. This situation has led to confusion and errors that continue to this day, and it is at odds with the intent of uniform standards.</p> <p>To resolve problems due to simultaneous use of two nearly identical versions of the foot, collaborative action is being taken by the National Institute of Standards and Technology (NIST) and the National Geodetic Survey (NGS), National Ocean Service (NOS), National Oceanic and Atmospheric Administration (NOAA). With the goal of providing national uniformity in the measurement of length, the U.S. survey foot will be phased out as part of the modernization of the National Spatial Reference System (NSRS). From this point forward, the international foot will be simply called the foot. A <a href="https://web.archive.org/web/20231128173251/https://www.federalregister.gov/documents/2019/10/17/2019-22414/deprecation-of-the-united-states-us-survey-foot">Federal Register Notice (FRN)</a> was issued to solicit public comment to ensure that this change is made in an orderly fashion with minimal disruption and a <a href="https://web.archive.org/web/20231128173251/https://www.federalregister.gov/documents/2020/10/05/2020-21902/deprecation-of-the-united-states-us-survey-foot">final determination</a> made to deprecate the use of the U.S. survey foot.</p> <p> </p> <div class="grid-row grid-gap"> <div class="grid-col text-align-center"> <figure class="align-center nist-image"><img alt="Department of Commerce Logo" height="218" loading="lazy" src="/web/20231128173251im_/https://www.nist.gov/sites/default/files/styles/220_x_220_limit/public/images/2017/09/20/doc_logo_1x1.gif?itok=gom2bQdf" typeof="foaf:Image" width="220"/><figcaption class="nist-image__caption"><div class="nist-image__caption-content" data-caption-editable="true"> </div> </figcaption></figure></div> <div class="grid-col"> <figure class="align-center nist-image"><img alt="NIST logo" height="207" loading="lazy" src="/web/20231128173251im_/https://www.nist.gov/sites/default/files/styles/480_x_480_limit/public/images/2017/11/08/nistident_cent_150ppi.jpg?itok=bM88cwxf" typeof="foaf:Image" width="450"/><figcaption class="nist-image__caption"><div class="nist-image__caption-content" data-caption-editable="true"> </div> </figcaption></figure></div> <div class="grid-col last text-align-center"> <figure class="align-center nist-image"><img alt="NOAA logo" height="220" loading="lazy" src="/web/20231128173251im_/https://www.nist.gov/sites/default/files/styles/220_x_220_limit/public/images/2019/08/13/1024px-noaa_logo.svg.png?itok=aSNFyn05" typeof="foaf:Image" width="220"/><figcaption class="nist-image__caption"><div class="nist-image__caption-content" data-caption-editable="true"> </div> </figcaption></figure></div> </div> <p class="text-align-center"> </p></div> </div> </div> </div> </div> </div> <div class="grid-row"> <div class="nist-resource-block nist-resource-block--first tablet:grid-col"> <div class="nist-resource-block__title-bar"> <div class="nist-resource-block__title"> <div class="nist-resource-block__icon"> <img aria-hidden="true" role="img" alt="decorative icon" src="/web/20231128173251im_/https://www.nist.gov/themes/custom/nist_www/img/resource-icons/megaphone-icon-2x.png"/> </div> <h2> <div class="string">Important Dates</div> </h2> </div> </div> <div class="nist-resource-block__content"> <div class="nist-block"> <div class="text-long"><ul><li>September 28, 2020 - Final determination FRN is anticipated to be published on or before this date and will present the public comments analysis and describe recommended actions to facilitate the deprecation of the U.S. survey foot.</li> <li>December 31, 2022 - The last day U.S. survey foot should be used.</li> <li>January 1, 2023 - The U.S. survey foot is deemed obsolete and superseded by the international foot (also known as the foot) equal to 0.304 8 meter exactly for all applications.</li> </ul></div> </div> </div> </div> <div class="nist-resource-block nist-resource-block--second nist-resource-block--green tablet:grid-col"> <div class="nist-resource-block__title-bar"> <div class="nist-resource-block__title"> <div class="nist-resource-block__icon"> <img aria-hidden="true" role="img" alt="decorative icon" src="/web/20231128173251im_/https://www.nist.gov/themes/custom/nist_www/img/resource-icons/link-icon-2x.png"/> </div> <h2> <div class="string">Useful Links</div> </h2> </div> </div> <div class="nist-resource-block__content"> <div class="nist-block"> <div class="text-long"><ul><li><a href="https://web.archive.org/web/20231128173251/https://www.nist.gov/trainingoutreach-events-calendar">Events</a></li> <li><a href="https://web.archive.org/web/20231128173251/https://www.nist.gov/frequently-asked-questions-faqs">Frequently Asked Questions (FAQs)</a></li> <li><a href="https://web.archive.org/web/20231128173251/https://www.nist.gov/pml/us-surveyfoot/resources">Resources</a></li> <li><a href="https://web.archive.org/web/20231128173251/https://www.nist.gov/revised-unit-conversion-factors">Revised Unit Conversion Factors</a></li> </ul></div> </div> </div> </div> </div> <div class="grid-container"> <div class="nist-page__region nist-page__region--content-bottom"> <div class="nist-block nist-block--contact"> <h2 class="nist-block__title">Contacts</h2> <div class="nist-contact"> <h3 class="nist-contact__heading">For information on standards development and maintenance of the U.S. survey foot, please contact:</h3> <ul class="nist-contact__items"> <li about="/people/elizabeth-benham" class="nist-contact__item"> <div class="nist-contact__name"><a href="/web/20231128173251/https://www.nist.gov/people/elizabeth-benham" title="View staff profile page">Elizabeth Benham</a></div> <div> <a href="https://web.archive.org/web/20231128173251/mailto:elizabeth.benham@nist.gov">elizabeth.benham@nist.gov</a> </div> <div> (301) 975-3690 </div> </li> <li class="nist-contact__item"> <div class="nist-contact__name"> Michael Dennis </div> <div> <a href="https://web.archive.org/web/20231128173251/mailto:michael.dennis@noaa.gov">michael.dennis@noaa.gov</a> </div> <div> (240) 533-9611 </div> <div> </div> </li> </ul> </div> <div class="nist-contact"> <h3 class="nist-contact__heading">For technical and historical information on usage of the foot, please contact:</h3> <ul class="nist-contact__items"> <li class="nist-contact__item"> <div class="nist-contact__name"> Michael Dennis </div> <div> <a href="https://web.archive.org/web/20231128173251/mailto:michael.dennis@noaa.gov">michael.dennis@noaa.gov</a> </div> <div> (240) 533-9611 </div> <div> </div> 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