Editing Metrication (section)

===United States (1830–present)===
{{Main|Metrication in the United States}}
[[File:Ferdinand Randolph Hassler LCCN2003655032.jpg|thumb|upright=0.75|Ferdinand Rudolph Hassler, first superintendent of the [[United States Coast and Geodetic Survey|United States Coast Survey]]|left]]
In 1805 a Swiss geodesist [[Ferdinand Rudolph Hassler]] brought copies of the French metre and kilogram to the United States.<ref>{{Cite web |url=http://www.f-r-hassler.ch/en/emigration/index.html |title=Emigration: Off to New Shores |website=E-Expo Ferdinand Rudolf Hassler |publisher=METAS |access-date=19 December 2017 |archive-date=12 February 2018 |archive-url=https://web.archive.org/web/20180212000054/http://www.f-r-hassler.ch/en/emigration/index.html |url-status=live }}</ref><ref name=":1">{{Cite journal|last=Cajori|first=Florian|date=1921|title=Swiss Geodesy and the United States Coast Survey|url=https://www.jstor.org/stable/6721|journal=The Scientific Monthly|volume=13|issue=2|pages=117–129|bibcode=1921SciMo..13..117C|issn=0096-3771|access-date=4 January 2021|archive-date=6 June 2021|archive-url=https://web.archive.org/web/20210606111103/https://www.jstor.org/stable/6721|url-status=live}}</ref> In 1830 the Congress decided to create uniform standards for length and weight in the United States.<ref name=":0">{{Cite web |url=http://www.f-r-hassler.ch/en/weights/index.html |title=Weights and Measures: New Standards for the USA |website=E-Expo Ferdinand Rudolf Hassler |publisher=METAS |access-date=19 December 2017 |archive-date=12 February 2018 |archive-url=https://web.archive.org/web/20180212000139/http://www.f-r-hassler.ch/en/weights/index.html |url-status=live }}</ref> [[Ferdinand Rudolph Hassler|Hassler]] was mandated to work out the new standards and proposed to adopt the [[metric system]].<ref name=":0" /> The Congress opted for the British Parliamentary Standard from 1758 and the Troy Pound of Great Britain from 1824 as length and weight standards.<ref name=":0" /> Nevertheless, the primary baseline of the Survey of the Coast (renamed the United States Coast Survey in 1836 and the [[United States Coast and Geodetic Survey]] in 1878) was measured in 1834 at [[Fire Island]] using four {{convert|2|m|adj=on}} iron bars constructed after Hassler's specification in the United Kingdom and brought back in the United States in 1815.<ref>{{Cite web |url=https://www.nist.gov/sites/default/files/documents/nvl/HasslerSP1068.pdf |title=NIST Special Publication 1068 Ferdinand Rudolph Hassler (1770–1843) A Twenty Year Retrospective, 1987–2007 |website=NIST |pages=51–52 |access-date=27 November 2017 |archive-date=31 January 2017 |archive-url=https://web.archive.org/web/20170131034513/https://www.nist.gov/sites/default/files/documents/nvl/HasslerSP1068.pdf |url-status=dead}}</ref><ref>{{Cite web |url=http://www.f-r-hassler.ch/en/interlude/index.html |title=Interlude in Europe: Ups... and Downs... |website=E-Expo Ferdinand Rudolf Hassler |publisher=METAS |access-date=19 December 2017 |archive-date=12 February 2018 |archive-url=https://web.archive.org/web/20180212000220/http://www.f-r-hassler.ch/en/interlude/index.html |url-status=live }}</ref><ref name=":1" /> All distances measured by the Survey of the Coast, Coast Survey, and Coast and Geodetic Survey were referred to the metre.<ref name=":2">{{cite journal |title=XIII. Results of the comparisons of the standards of length of England, Austria, Spain, United States, Cape of Good Hope, and of a second Russian standard, made at the Ordnance Survey Office, Southampton. With a preface and notes on the Greek and Egyptian measures of length by Sir Henry James |journal=Philosophical Transactions of the Royal Society of London |date=31 December 1873 |volume=163 |pages=445–469 |doi=10.1098/rstl.1873.0014 |doi-access=free}}</ref><ref name=":3">{{Cite book|last=Hassler|first=Ferdinand Rudolf|date=1825|title=Transactions of the American Philosophical Society|url=https://www.biodiversitylibrary.org/page/4482470|access-date=|volume=2|page=252|archive-date=8 April 2023|archive-url=https://web.archive.org/web/20230408175517/https://www.biodiversitylibrary.org/page/4482470|url-status=live}}</ref> In 1866 the [[United States Congress]] passed a bill making it lawful to use the metric system in the United States. The bill, which was permissive rather than mandatory in nature, defined the metric system in terms of [[United States customary units|customary units]] rather than with reference to the international prototype metre and kilogram.<ref>{{cite web
 |url=http://lamar.colostate.edu/~hillger/laws/metric-act-bill.html 
 |title=H.R. 596, An Act to authorize the use of the metric system of weights and measures 
 |author=29th Congress of the United States, Session 1 
 |date=13 May 1866 |access-date=19 May 2011 |url-status=dead 
 |archive-url=https://web.archive.org/web/20150705015307/https://lamar.colostate.edu/~hillger/laws/metric-act-bill.html 
 |archive-date=5 July 2015}}</ref><ref name=Barbrowetal/>{{rp|10–13}} Ferdinand Rudolph Hassler's use of the metre in coastal surveying, which had been an argument for the introduction of the [[Metric Act of 1866]] allowing the use of the metre in the United States, probably also played a role in the choice of the metre as international scientific unit of length and the proposal by the [[International Association of Geodesy|European Arc Measurement]] (German: ''Europäische Gradmessung'') to “establish a European [[International Bureau of Weights and Measures|international bureau for weights and measures]]”.<ref name=":3" /><ref name=":2" /><ref>{{Cite web|title=Metric Act of 1866 – US Metric Association|url=https://usma.org/laws-and-bills/metric-act-of-1866#locale-notification|access-date=4 January 2021|website=usma.org|archive-date=28 February 2021|archive-url=https://web.archive.org/web/20210228052918/https://usma.org/laws-and-bills/metric-act-of-1866#locale-notification|url-status=live}}</ref><ref>{{Cite book|last=|first=|url=http://gfzpublic.gfz-potsdam.de/pubman/item/escidoc:108187:4/component/escidoc:272449/Generalbericht.mitteleurop%C3%A4ische.Gradmessung%201867.pdf|title=Bericht über die Verhandlungen der vom 30. September bis 7. October 1867 zu BERLIN abgehaltenen allgemeinen Conferenz der Europäischen Gradmessung|publisher=Central-Bureau der Europäischen Gradmessung|year=1868|isbn=|location=Berlin|pages=123–134|language=de}}</ref>

By 1893, the reference standards for customary units had become unreliable. Moreover, the United States, being a signatory of the [[Metre Convention]] was in possession of national prototype metres and kilograms that were calibrated against those in use elsewhere in the world. This led to the [[Mendenhall Order]] which redefined the customary units by referring to the national metric prototypes, but used the conversion factors of the 1866 act.<ref name="Barbrowetal">{{cite book
 |url         = https://www.nist.gov/pml/pubs/sp447/index.cfm
 |title       = Weights and Measures Standards of the United States: A brief history
 |first1      = Louis E.
 |last1       = Barbrow
 |first2      = Lewis V.
 |last2       = Judson
 |publisher   = NIST
 |year        = 1976
 |access-date  = 19 May 2011
|url-status     = dead
 |archive-url  = https://web.archive.org/web/20110603064530/https://www.nist.gov/pml/pubs/sp447/index.cfm
 |archive-date = 3 June 2011
}}</ref>{{rp|16–20}} In 1896, a bill that would make the metric system mandatory in the United States was presented to Congress. Twenty-three of the 29 people who gave evidence before the congressional committee who were considering the bill were in favor of it, but six were against. Four of these six dissenters represented manufacturing interests and the other two were from the United States Revenue service. The grounds cited were the cost and inconvenience of the change-over. The bill was not enacted. Subsequent bills suffered a similar fate.<ref name="PopularScience" />

The United States mandated the acceptance of the metric system in 1866 for commercial and legal proceedings, without displacing their customary units.<ref name="United States Metric Laws and Treaties">{{cite web |url=http://ts.nist.gov/WeightsAndMeasures/Metric/upload/HR-596-Metric-Law-1866.pdf |title=Metric Act of 1866 |publisher=Metric Program, Weights and Measures Division, United States National Institute of Standards, Technology and Technology |access-date=10 November 2009 |url-status=dead |archive-url=https://web.archive.org/web/20100527161529/http://ts.nist.gov/WeightsAndMeasures/Metric/upload/HR-596-Metric-Law-1866.pdf |archive-date=27 May 2010}}<br /> {{cite web | title = U.S. Metric System (SI) Legal Resources | url = http://ts.nist.gov/WeightsAndMeasures/Metric/Federal_Metric_Policy.cfm#legal | publisher = Metric Program, Weights and Measures Division, United States National Institute of Standards, Technology and Technology | access-date = 11 November 2009 | url-status = dead | archive-url = https://web.archive.org/web/20090801172441/http://ts.nist.gov/WeightsAndMeasures/Metric/Federal_Metric_Policy.cfm#legal | archive-date = 1 August 2009 | df = dmy-all}}</ref> The non-mandatory nature of the adoption of the SI has resulted in a much slower pace of adoption in the US than in other countries.<ref>{{cite journal |last1=Smith |first1=Jeanette C. |title=Take Me to Your Liter |journal=Journal of Government Information |date=September 1998 |volume=25 |issue=5 |pages=419–438 |doi=10.1016/S1352-0237(98)00030-6}}</ref>

In 1971, the US [[National Institute of Standards and Technology|National Bureau of Standards]] completed a three-year study of the impact of increasing worldwide metric use on the US. The study concluded with a report to Congress entitled ''[[A Metric America&nbsp;– A Decision Whose Time Has Come]]''. Since then metric use has increased in the US, principally in the manufacturing and educational sectors. Public Law 93-380, enacted 21 August 1974, states that it is the policy of the US to encourage educational agencies and institutions to prepare students to use the metric system of measurement with ease and facility as a part of the regular education program. On 23 December 1975, President Gerald Ford signed Public Law 94–168, the [[Metric Conversion Act]] of 1975. This act declares a national policy of coordinating the increasing use of the metric system in the US. It established a US Metric Board whose functions as of 1 October 1982 were transferred to the Dept of Commerce, Office of Metric Programs, to coordinate the voluntary conversion to the metric system.<ref>{{Cite book
 |editor = Howard B. Bradley
 |title = Petroleum Engineering Handbook
 |pages = 1–69
 |year = 1987
 |publisher = Society of Petroleum Engineers
 |isbn = 978-1555630102
}}</ref>

In January 2007 [[NASA]] decided to use metric units for all future Moon missions, in line with the practice of other space agencies.<ref name="MetricMoon">{{cite web
 |url=https://science.nasa.gov/science-news/science-at-nasa/2007/08jan_metricmoon/
 |title=Metric Moon
 |year=2007
 |publisher=[[NASA]]
 |access-date=6 April 2010
|archive-date=11 July 2010
|archive-url=https://web.archive.org/web/20100711000119/http://science.nasa.gov/science-news/science-at-nasa/2007/08jan_metricmoon/
 |url-status=dead
}}</ref>