Editing Kilometre

{{short description|Unit of length equal to 1,000 metres}}
{{Redirect|km|other uses|KM (disambiguation)}}
{{Use dmy dates|date=March 2023}}
{{Use British English|date=September 2020}}
{{Infobox unit
| name     = kilometre
| image    = 25 April Tagus bridge (10480970823).jpg
| caption  = The main span of the [[25 de Abril Bridge]] is {{convert|1.013|km|m}}.
| symbol   = km
| standard = [[SI]]
| quantity = [[length]]
| units1   = [[SI base units]]
| inunits1 = {{val|1000|ul=m}}
| units2   = [[imperial units|imperial]]/[[US customary units|US]]&nbsp;units
| inunits2 = {{val|0.62137|ul=mi}}<br /><!---->&emsp;{{val|1093.6|ul=yd}}<br /><!---->&emsp;{{val|3280.8|ul=ft}}
| units3   = nautical&nbsp;units
| inunits3 = {{convert|1|km|nmi|disp=out|lk=on|sigfig=5|comma=gaps}}
}}

The '''kilometre''' ([[SI]] symbol: '''km'''; {{IPAc-en|ˈ|k|ɪ|l|ə|m|iː|t|ər}} or {{IPAc-en|k|ɪ|ˈ|l|ɒ|m|ə|t|ər}}), spelt<!-- no, "spelt" is not a mistake --> '''kilometer''' in [[American English|American]] and [[Philippine English]], is a [[unit of length]] in the [[International System of Units]] (SI), equal to one thousand [[metre]]s ([[kilo-]] being the [[SI prefix]] for {{val|1000}}). It is the preferred measurement unit to express distances between geographical places on land in most of the world; notable exceptions are the United States and the United Kingdom where the [[statute mile]] is used.

== Pronunciation==
{{more citations needed section|date=October 2011}}
There are two common pronunciations for the word.<ref>{{Citation |last=Jones |first=Daniel |author-link=Daniel Jones (phonetician) |title=English Pronouncing Dictionary |editor=Peter Roach |editor2=James Hartmann |editor3=Jane Setter |place=Cambridge |publisher=Cambridge University Press |orig-year=1917 |year=2003 |isbn=3-12-539683-2 }}</ref><!--Click the link for why /r/'s are included though they aren't phonemic in BrE, AusE, etc.-->
# {{IPAc-en|ˈ|k|ɪ|l|ə|m|iː|t|ər|,_|-|l|oʊ|-}}
# {{IPAc-en|k|ᵻ|ˈ|l|ɒ|m|ᵻ|t|ər}}

The first pronunciation follows a pattern in English whereby SI units are pronounced with the stress on the first syllable (as in [[kilogram]], [[kilojoule]] and [[kilohertz]]) and the pronunciation of the actual base unit does not change irrespective of the prefix (as in [[centimetre]], [[millimetre]], [[nanometre]] and so on). It is generally preferred by the British Broadcasting Corporation (BBC), the Canadian Broadcasting Corporation (CBC), and the Australian Broadcasting Corporation (ABC).{{citation needed|date=February 2015}}

Many other users, particularly in countries where SI (the metric system) is not widely used, use the second pronunciation with stress on the second syllable.<ref>{{Cite news| url=http://entertainment.timesonline.co.uk/tol/arts_and_entertainment/tv_and_radio/article3586220.ece | archive-url=https://web.archive.org/web/20110307091048/http://entertainment.timesonline.co.uk/tol/arts_and_entertainment/tv_and_radio/article3586220.ece | url-status=dead | archive-date=7 March 2011 | work=The Times | location=London | title=Correct pronunciation on the radio | first=Roland | last=White | date=23 March 2008 |access-date=7 May 2010}}</ref><ref>{{cite web|url=http://www.merriam-webster.com/dictionary/kilometer |title=Kilometer – Definition and More from the Free Merriam-Webster Dictionary |publisher=Merriam-Webster |access-date=2014-08-05}}</ref> The second pronunciation follows the stress pattern used for the names of measuring instruments (such as ''micrometer'', ''barometer'', ''thermometer'', ''tachometer,'' and ''speedometer''). The contrast is even more obvious in countries that use the American spelling of the word ''metre''. This pronunciation is irregular because it makes the kilometre the only SI unit with the stress on the second syllable.

After Australia introduced the metric system in 1970, the first pronunciation was declared official by the government's Metric Conversion Board. However, the Australian prime minister at the time, [[Gough Whitlam]], insisted that the second pronunciation was the correct one because of the Greek origins of the two parts of the word.<ref>{{Cite web |url=http://www.cimms.ou.edu/~doswell/peeves/Discussions.html |title=E-mail Discussions on "Peeves" Topics |author=[[Charles A. Doswell III]] |website=[[Cooperative Institute for Mesoscale Meteorological Studies]] - [[University of Oklahoma]] |access-date=2014-08-05 |archive-url=https://web.archive.org/web/20081022055855/http://www.cimms.ou.edu/~doswell/peeves/Discussions.html |archive-date=2008-10-22 |url-status=dead}}</ref>

== Equivalence to other units of length ==
: {| 
|-
| rowspan="8" style="vertical-align:top;"| 1 kilometre
| ≡
| align=right | {{val|1000}}
| [[metre]]s
|-
| ≈
| align=right | {{val|3281}}
|[[Foot (unit)|feet]]
|-
| ≈
| align=right | {{val|1094}}
| [[yard]]s
|-
| ≈
| align=right | 0.621
| [[mile]]s
|-
| ≈
| align=right | 0.540
| [[nautical mile]]s
|-
| ≈
| align=right | {{val|6.68|e=-9}}
| [[astronomical unit]]s{{efn|One astronomical unit is currently accepted to be equal to {{val|149597870691|30|u=m}}.}}
|-
| ≈
| align=right | {{val|1.06|e=-13}}
| [[light-year]]s{{efn|A light-year is equal to {{val|9.4607304725808|e=12|u=km}} the distance light travels through vacuum in one [[Julian year (astronomy)|year]] (365.25 days).}}
|-
| ≈
| align=right | {{val|3.24|e=-14}}
| [[parsec]]s
|}

== History ==
[[File:Division of the meridien.PNG|thumb|480px|right|Historical divisions of the meridian in France]]

By a decree of 8 May 1790, the French [[National Constituent Assembly (France)|National Constituent Assembly]] ordered the [[French Academy of Sciences]] to develop a new measurement system. In August 1793, the French [[National Convention]] decreed the [[metre]] as the sole length measurement system in the French Republic and it was based on {{Sfrac|1|10}} millionth of the distance from the [[orbital pole]]s (either North or South) to the [[Equator]], this being a truly internationally based unit. The first name of the kilometre was "Millaire".
Although the metre was formally defined in 1799, the [[myriametre]] ({{val|10000}}&nbsp;metres) was preferred to the "kilometre" for everyday use. The term "''myriamètre''" appeared a number of times in the text of Develey's book ''Physique d'Emile: ou, Principes de la science de la nature'',<ref>{{cite book |title = Physique d'Emile: ou, Principes de la science de la nature |volume = 1 |first1 = Emmanuel |last1 = Develey |year = 1802 |location = Paris |lang=fr |url = https://books.google.com/books?id=AFsIAAAAIAAJ&pg=PA90 }}</ref> (published in 1802), while the term ''kilometre'' only appeared in an appendix. French maps published in 1835 had scales showing ''myriametres'' and "''lieues de Poste''{{-"}} (Postal leagues of about {{val|4288}}&nbsp;metres).<ref>{{cite map |publisher = Laguillermie et Rambos |title = Map of the department of Hautes Pyrénées |year = 1835 |url= http://www.mereweather.net/hautespyrenees.htm |series = France Pittoresque |language= fr |access-date = 21 September 2012}}</ref>

The Dutch, on the other hand, adopted the kilometre in 1817 but gave it the local name of the ''mijl''.<ref>{{cite book |url = https://archive.org/details/allereerstegron00ramagoog |title = Allereerste Gronden der Cijferkunst |author = Jacob de Gelder |location = 's-Gravenhage and Amsterdam |language = nl |year = 1824 |pages = [https://archive.org/details/allereerstegron00ramagoog/page/n364 155]–156 |publisher = de Gebroeders van Cleef |trans-title=Introduction to Numeracy |access-date =2 March 2011}}</ref> It was only in 1867 that the term "''kilometer''{{-"}} became the only official unit of measure in the Netherlands to represent {{val|1000}}&nbsp;metres.<ref>{{Cite news |url= http://resources2.kb.nl/010285000/pdf/DDD_010287511.pdf |newspaper= De Locomotief. Nieuws, handels en Advertentie-blad |page= 2 |date= 12 August 1869 |title= [News from] Nederland |url-status= dead |archive-url= https://web.archive.org/web/20170227120542/http://resources2.kb.nl/010285000/pdf/DDD_010287511.pdf |archive-date = 27 February 2017}}</ref>

Two German textbooks dated 1842<ref name=Europa1842>{{cite web |url = http://home.fonline.de/fo0126//geschichte/groessen/mas1.htm |title = Amtliche Maßeinheiten in Europa 1842 |language = de |trans-title=Official units of measure in Europe 1842 |access-date = 26 March 2011}} Text version of Malaisé's book.</ref><ref>{{cite book |url = http://home.fonline.de/rs-ebs/geschichte/buch/titel.htm |title = Theoretisch-practischer Unterricht im Rechnen |language = de |trans-title=Theoretical and practical instruction in arithmetic |author = Ferdinand Malaisé |place = München |year = 1842 |pages = 307–322 |access-date = 26 March 2011}}</ref> and 1848<ref>{{cite book |url = http://commons.wikimedia.org/wiki/Category:Lehrbuch_des_gesammten_Rechnens_f%C3%BCr_die_vierte_Classe_der_Hauptschulen_in_den_k.k._Staaten_(Franz_Mozhnik) |first1 = Franz |last1 = Mozhnik |title = Lehrbuch des gesammten Rechnens für die vierte Classe der Hauptschulen in den k.k. Staaten. |language = de |trans-title=Arithmetic textbook for the fourth class in the [Austrian] Imperial and [Hungarian] Royal states |publisher = Im Verlage der k.k. Schulbücher Verschleiß-Administration |location = [[Vienna]] |year = 1848 |access-date = 19 July 2013 |at = Das Wegmaß}}</ref> respectively give a snapshot of the use of the kilometre across Europe: the kilometre was in use in the Netherlands and in Italy, and the myriametre was in use in France.

In 1935, the [[International Committee for Weights and Measures]] (CIPM) officially abolished the prefix "myria-" and with it the "myriametre", leaving the kilometre as the recognised unit of length for measurements of that magnitude.<ref>{{cite book |title = The Basis of Measurement – Volume 2 – Metrication and Current Practice. |first1 = Thomas |last1 = McGreevy |editor1-first = Peter |editor1-last = Cunningham |publisher = Picton |isbn = 0-948251-84-0 |year = 1997}}</ref>

The symbol '''km''' for the kilometre is in lower case and has been standardised by the [[BIPM]].<ref>{{cite web |url=https://www.oxfordlearnersdictionaries.com/definition/english/kilometre?q=kilometre |title=Kilometre |website=Oxford Learner's Dictionaries |access-date=1 November 2019}}</ref><ref>{{cite web |title=The International System of Units (SI) |url=https://www.bipm.org/utils/common/pdf/si-brochure/SI-Brochure-9-EN.pdf#page=33 |publisher=International Bureau of Weights and Measures (BIPM) |access-date=8 January 2020 |pages=147–149 |date=2019}}</ref> A slang term for the kilometre in the US, UK, and Canadian militaries is ''[[wikt:klick#Etymology 1|klick]]''.<ref>{{cite web |title=MARINE CORPS JARGON |url=http://www.hqmc.marines.mil/Portals/143/Docs/Onboarding/Marine%20jargon.pdf |publisher=hqmc.marines.mil |access-date=3 March 2017}}</ref>

== Kilometre records ==
Some sporting disciplines feature {{val|1000|u=m}} (one-kilometre) races in major events (such as the [[Olympic Games]]). In some disciplines—although world records are catalogued—one-kilometre events remain a minority.

{|class="wikitable sortable"
|+1&nbsp;km world records for various sporting disciplines
|-
!Discipline
!Name
!Time (min:sec)
!Location
!Date
!Comments
|-
| Running (M)
|[[Noah Ngeny]]
|align=right|2:11.96<ref>{{Cite web |title=Stats {{!}} World Athletics {{!}} World Athletics |url=https://worldathletics.org/records/by-progression/13501 |access-date=2024-10-07 |website=worldathletics.org}}</ref>
|[[Rieti, Italy]]
|align=right|{{dts|5 Sep 1999}}
|Not an Olympic event
|-
|Running (F)
|[[Svetlana Masterkova]]
|align=right|2:28.98<ref>{{Cite web |title=Stats {{!}} World Athletics {{!}} World Athletics |url=https://worldathletics.org/records/by-progression/3517 |access-date=2024-10-07 |website=worldathletics.org}}</ref>
|[[Brussels]]
|align=right|{{dts|23 Aug 1996}}
|Not an Olympic event
|-
|[[Speed skating]] (M)
|[[Pavel Kulizhnikov]]
|align=right|1:05.69
|[[Salt Lake City]]
|align=right|{{dts|15 Feb 2020}}
|
|-
|[[Speed skating]] (F)
|[[Brittany Bowe]]
|align=right|1:11.61
|[[Utah Olympic Oval|Salt Lake City]]
|align=right|{{dts|9 Mar 2019}}
|
|-
|[[Track cycling]] (M)
|[[François Pervis]]
|align=right|56.303<ref>{{cite web|title=Pervis sets new kilometre world record in Mexico|date=8 December 2013 |url=http://www.cyclingnews.com/news/pervis-sets-new-kilometre-world-record-in-mexico|publisher=Cycling News|access-date=17 October 2021}}</ref>
|[[Aguascalientes City|Aguascalientes, Mexico]]
|align=right|{{dts|7 Dec 2013}}
|No official {{val|1000|u=m}} women's record
|}

== See also ==
* [[Conversion of units]], for comparison with other units of length
* [[Cubic metre]]
* [[Metric prefix]]
* [[Mileage (disambiguation)|Mileage]]
* [[Odometer]]
* [[Orders of magnitude (length)]]
* [[Square kilometre]]

== Notes ==
{{Notelist}}

== References ==
{{Reflist}}

== External links ==
{{Spoken Wikipedia|kilometre.ogg|date=2013-06-27}}
* {{commons category-inline|Distance indicators}}

{{SI units of length}}

[[Category:Metre]]
[[Category:Orders of magnitude (length)|+03]]
[[Category:1000 (number)]]