View source for Furlong

{{refimprove|date=June 2025}}
{{Other uses}}
{{short description|Unit of length equal to 660 feet or about 201 metres}}
{{Use dmy dates|date=August 2020}}
{{Infobox unit
| image    = Naypyitaw Tollbooth (sign crop).jpg
| caption  = Present-day use of furlongs on a highway sign near [[Yangon]]
| standard = [[imperial units|imperial]]/[[United States customary units|US]]&nbsp;units
| quantity = [[length]]
| units1   = imperial/US&nbsp;units
| inunits1 = 220&nbsp;[[yard|yd]] or {{frac|1|8}}&nbsp;mi
| units2   = [[metric system|metric]] ([[SI]]) units
| inunits2 = {{convert|220|yd|m|4|lk=on|disp=out}}
}}
{{Anthropic_Farm Units}}

A '''furlong''' is a measure of [[distance]] in [[imperial units]] and [[United States customary units]] equal to one-eighth of a [[mile]], equivalent to any of 660&nbsp;[[foot (unit)|feet]], 220&nbsp;[[yard]]s, 40&nbsp;[[rod (unit)|rods or perches]], 10&nbsp;[[chain (unit)|chains]], or approximately 201&nbsp;[[metre]]s. It is now mostly confined to use in horse racing, where in many countries{{which|date=September 2024}} it is the standard measurement of race lengths, and agriculture, where it is used to measure rural field lengths and distances. 

In the United States, some states use older definitions for surveying purposes, leading to variations in the length of the furlong of two parts per million, or about {{convert|0.4|mm|in|frac=64|abbr=off}}. This variation is small enough to not have practical consequences in most applications. 
 
Using the [[International yard and pound|international definition of the yard]] as exactly 0.9144&nbsp;metres, one furlong is 201.168&nbsp;metres, and five furlongs are about 1&nbsp;[[kilometre]] ({{convert|5/8|mi|5|disp=out}} exactly).

==History==
The name ''furlong'' derives from the [[Old English]] words ''{{lang|ang|furh}}'' ([[furrow]]) and ''{{lang|ang|lang}}'' (long).<ref>{{Cite EB1911 |wstitle=Furlong |volume=11 |page=358}}</ref> Dating back at least to early [[Anglo-Saxon]] times, it originally referred to the length of the furrow in one [[acre]] of a ploughed [[open-field system|open field]] (a medieval communal field which was divided into strips). The furlong (meaning furrow length) was the distance a team of oxen could plough without resting. This was standardised to be exactly 40&nbsp;rods or 10&nbsp;chains. The system of long furrows arose because turning a team of oxen pulling a heavy plough was difficult. This offset the drainage advantages of short furrows and meant furrows were made as long as possible. An acre is an area that is one furlong long and one [[Chain (unit)|chain]] (66&nbsp;feet or 22&nbsp;yards) wide. For this reason, the furlong was once also called an '''acre's length''',<ref>{{cite book |title=[[The Winter's Tale]] |first=William |last=Shakespeare |author-link=William Shakespeare |edition=unabridged|publisher=Courier Dover|year=2000 |isbn=9780486411187| page=5|quotation=footnote 17: ''heat an acre''; run a heat or course of an acre's length, "acre" being used as a lineal measure, equivalent to a furlong.}} {{Folger inline|WT|1|2|123|bare=true}}</ref> though in modern usage an area of one acre can be of any shape. The term furlong, or shot, was also used to describe a grouping of adjacent strips within an open field.<ref>{{cite book |url=https://books.google.com/books?id=1tgk_UNST2kC&q=furlong%20shot%20strip%20field&pg=PR28 |title=The English Village Community Examined in Its Relation to the Manorial and Tribal Systems and to the Common Or Open Field System of Husbandry: An Essay in Economic History|first=Frederic |last=Seebohm |publisher=Cambridge University Press |date=8 December 2011|page=4|isbn=9781108036344}}</ref>

Among the early Anglo-Saxons, the rod was the fundamental unit of land measurement. A furlong was 40&nbsp;rods; an acre 4 by 40&nbsp;rods, or 4&nbsp;rods by 1&nbsp;furlong, and thus 160&nbsp;square rods; there are 10&nbsp;acres in a square furlong. At the time, the Saxons used the [[Foot_(unit)#England|North German foot]], which was about 10&nbsp;percent longer than the foot of the [[International yard and pound|international 1959 agreement]]. When England [[Composition of Yards and Perches|changed to a shorter foot]] in the late 13th&nbsp;century, rods and furlongs remained unchanged, since property boundaries were already defined in rods and furlongs. The only thing that changed was the number of feet and yards in a rod or a furlong, and the number of square feet and square yards in an acre. The definition of the rod went from 15&nbsp;old feet to {{frac|16|1|2}}&nbsp;new feet, or from 5&nbsp;old yards to {{frac|5|1|2}}&nbsp;new yards. The furlong went from 600 old feet to 660 new feet, or from 200&nbsp;old yards to 220&nbsp;new yards. The acre went from 36,000&nbsp;old square feet to 43,560&nbsp;new square feet, or from 4,000&nbsp;old square yards to 4,840&nbsp;new square yards.<ref>{{cite book|last=Zupko|first=Ronald Edward|author-link=Ronald Edward Zupko|title=British weights & measures: a history from antiquity to the seventeenth century|url=https://books.google.com/books?id=pWUgAQAAIAAJ|year=1977|publisher=University of Wisconsin Press|isbn=978-0-299-07340-4|pages=10–11, 20–21}}</ref>  

The furlong was historically viewed as being equivalent to the [[Stadion (unit)|Roman stade (''stadium'')]],<ref>Compare [[Josephus]], ''[[Antiquities of the Jews|Antiquities]]'' (15.11.3), who writes of the [[Temple Mount]] in Jerusalem that it was encompassed by a wall which measured one ''stadion'' ([[Greek language|Gr.]] στάδιον) to each angle, a word translated in English as "furlong".</ref> which in turn derived from the [[Ancient Greek units of measurement|Greek system]].{{fact|date=August 2025}}

In the Roman system, there were 625&nbsp;feet to the ''stadium'', eight ''stadia'' to the mile, and 1½&nbsp;miles to the [[league (unit)|league]]. A league was considered to be the distance a man could walk in one hour, and the mile (from ''mille'', meaning "thousand") consisted of 1,000&nbsp;''passus'' (paces, five&nbsp;feet, or double-step).{{fact|date=August 2025}}

After the fall of the [[Western Roman Empire]], medieval Europe continued with the Roman system, which the people proceeded to diversify, leading to serious complications in trade, taxation, etc.{{or|date=August 2025}} Around the year 1300, by royal decree, England standardized a long list of measures.{{fact|date=August 2025}} Among the important units of distance and length at the time were the [[foot (unit)|foot]], [[yard]], [[rod (unit)|rod]] (or pole), furlong, and the [[mile]]. The rod was defined as {{frac|5|1|2}}&nbsp;yards or {{frac|16|1|2}}&nbsp;feet, and the mile was eight furlongs, so the definition of the furlong became 40&nbsp;rods and that of the mile became 5,280&nbsp;feet (eight furlongs/mile times 40&nbsp;rods/furlong times {{frac|16|1|2}}&nbsp;feet/rod). The invention of the [[Gunter's chain|measuring chain]] in the 1620s led to the introduction of an intermediate unit of length, the chain of 22&nbsp;yards, being equal to four rods, and to one-tenth of a furlong.{{fact|date=August 2025}}

A description from 1675 states, "Dimensurator or Measuring Instrument whereof the mosts usual has been the Chain, and the common length for English Measures four Poles, as answering indifferently to the Englishs Mile and Acre, 10 such Chains in length making a Furlong, and 10 single square Chains an Acre, so that a square Mile contains 640&nbsp;square Acres."<ref name="ogleby1670">{{cite web | url=https://archive.org/details/bim_early-english-books-1641-1700_britannia-volume-the-fi_ogilby-john_1675/mode/1up | title=Brittania Volume the First: or, an Illustration of the Kingdom of England and Diminion of Wales: by a Geographical and Historical Description Thereof | date=1675 | accessdate=25 August 2025 | last=Ogilby | first=John}}</ref>

The official use of the furlong was abolished in the United Kingdom under the [[Weights and Measures Acts (UK)|Weights and Measures Act]] 1985, an act that also abolished the official use of many other traditional units of measurement.{{fact|date=August 2025}}

==Use==
[[File:Milepost 358-6 on Yangon-Mandalay Expressway.JPG|right|thumb|Mileposts on the Yangon–Mandalay Expressway use miles followed by furlongs (this sign has numbers that do not reflect these measurements)]]
In [[Myanmar]] furlongs are currently used in conjunction with miles to indicate distances on highway signs. Mileposts on the [[Yangon–Mandalay Expressway]] use miles and furlongs.

[[File:036175 5 furlong.jpg|right|thumb|The five-furlong (1000&nbsp;m) post on [[Epsom Downs Racecourse]]]]
In the rest of the world the furlong has very limited use, with the notable exception of [[horse racing]] in most English-speaking countries, including Canada and the United States. The distances for [[Horse racing#Australia|horse racing]] in Australia were converted to metric in 1972<ref>{{cite web |url=http://museumvictoria.com.au/about/mv-news/2010/how-to-measure-a-racehorse/ |title=How to measure a racehorse |year=2010 |publisher=Museum Victoria|archive-url=https://web.archive.org/web/20150621172623/http://museumvictoria.com.au/about/mv-news/2010/how-to-measure-a-racehorse/ |archive-date=21 June 2015 |url-status=dead }}</ref> and the term survives only in slang.{{cn|date=October 2024}} In the United Kingdom,<ref>[http://www.sportinglife.com/racing/goodwood/course/ Example of the use of furlongs in horse racing] {{webarchive|url=https://web.archive.org/web/20110629220021/http://www.sportinglife.com/racing/goodwood/course/ |date=29 June 2011 }}</ref> Ireland, Canada, and the United States, races are still given in miles and furlongs. Also distances along English canals navigated by [[narrowboat]]s are commonly expressed in miles and furlongs.

The city of [[Roads and expressways in Chicago|Chicago's street numbering system]] allots a measure of 800 address units to each mile, in keeping with the city's system of eight blocks per mile. This means that every block in a typical Chicago neighborhood (in either north–south or east–west direction but rarely both) is approximately one furlong in length. City blocks in the [[Hoddle Grid]] of [[Melbourne]] are also one furlong in length. [[Salt Lake City]]'s blocks are each a square furlong in the downtown area. The blocks become less regular in shape farther from the center, but the numbering system (800&nbsp;units to each mile) remains the same everywhere in [[Salt Lake County, Utah|Salt Lake County]]. Blocks in central [[Logan, Utah]], and in large sections of [[Phoenix, Arizona]], are similarly a square furlong in extent (eight to a mile, which explains the series of freeway exits: 19th Ave, 27th, 35th, 43rd, 51st, 59th&nbsp;...). 

Much of [[Ontario]], Canada, was originally surveyed on a ten-furlong grid, with major roads being laid out along the grid lines. Now that distances are shown on road signs in kilometres, these major roads are almost exactly two kilometres apart. The exits on highways running through [[Toronto]], for example, are generally at intervals of two kilometres.<ref>[https://www.empm.ca/reports/Title%20Searches.pdf The Importance of Title Searches] {{webarchive|url=https://web.archive.org/web/20070709160457/http://www.empm.ca/reports/Title%20Searches.pdf |archive-url=https://web.archive.org/web/20050131212216/http://empm.ca/reports/Title%20Searches.pdf |archive-date=2005-01-31 |url-status=live |date=9 July 2007 }}</ref><ref>{{Cite web |url=http://wall-arm.ca/2011/04/land-titles-vs-land-registry |title=Land Titles vs. Land Registry |access-date=26 August 2015 |archive-date=10 December 2019 |archive-url=https://web.archive.org/web/20191210085101/https://wall-arm.ca/2011/04/land-titles-vs-land-registry |url-status=dead }}</ref>

The [[Bangor City Forest]] in Bangor, Maine has its trail system marked in miles and furlongs.

The furlong is also a base unit of the humorous [[FFF system]] of units.<ref name="SKB">[[Stan Kelly-Bootle]], "[http://portal.acm.org/citation.cfm?id=1229919 As Big as a Barn?]", ''[[ACM Queue]]'', March 2007, pp. 62–64.</ref>

==Definition of length==
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The exact length of the furlong varies slightly among English-speaking countries. In Canada<ref>
[http://laws-lois.justice.gc.ca/eng/acts/W-6/ Weights and Measures Act, R.S.C., 1985], as amended; Schedule&nbsp;II, Canadian Units of Measurement.
</ref> and the United Kingdom,<ref>
[http://www.legislation.gov.uk/ukpga/1985/72/schedule/1/part/VI Weights and Measures Act 1985], as amended; Schedule&nbsp;1,
Part&nbsp;VI, Definitions of certain units which may not be used for trade except as supplementary indications.
</ref> which define the furlong in terms of the international yard of exactly 0.9144&nbsp;metres, a furlong is 201.168&nbsp;m. Australia<ref>
[http://www.comlaw.gov.au/Series/F1999B00110 National Measurement Regulations 1999], Statutory Rules 1999 No. 110 as amended, Schedule&nbsp;11, Conversion Factors.
</ref> does not formally define the furlong, but it does define the chain and link in terms of the international yard.

The United States previously defined the furlong, chain, rod, and [[link (unit)|link]] in terms of the [[U.S. survey foot]] of exactly {{fract|1200|3937}}&nbsp;metre,<ref>
NIST Special Publication 811, Guide for the Use of the International System of Units (SI), [http://physics.nist.gov/Pubs/SP811/appenB.html Appendix&nbsp;B], B.6, U.S. survey foot and mile. [[National Institute for Standards and Technology]], U.S. Department of Commerce, 2008.</ref> resulting in a furlong approximately 201.1684&nbsp;m long. The difference of approximately two parts per million between the old U.S. value and the "international" value was insignificant for most practical measurements.

In October 2019, [[U.S. National Geodetic Survey]] and [[National Institute of Standards and Technology]] announced their joint intent to retire the U.S. survey foot, with effect from the end of 2022. The furlong in U.S. Customary units is thereafter defined based on the International 1959 foot, giving the length of the furlong as exact 201.168&nbsp;meters in the United States as well.<ref>{{cite web |title=NGS and NIST to Retire U.S. Survey Foot after 2022 |url=https://www.ngs.noaa.gov/web/news/us-survey-foot.shtml |publisher=National Geodetic Survey |date=31 October 2019}}</ref><ref>{{cite web |title=U.S. Survey Foot: Revised Unit Conversion Factors |url=https://www.nist.gov/pml/us-surveyfoot/revised-unit-conversion-factors |publisher=NIST |date=16 October 2019}}</ref>

==References==
{{Reflist}}
{{Wiktionary}}

{{Imperial units}}
{{United States Customary Units}}

[[Category:Customary units of measurement in the United States]]
[[Category:Horse racing terminology]]
[[Category:Imperial units]]
[[Category:Road transport in Myanmar]]
[[Category:Surveying]]
[[Category:Units of length]]