The mile, sometimes the international mile or statute mile to distinguish it from other miles, is a imperial unit and United States customary unit of length; both are based on the older English unit of length equal to 5,280 English feet, or 1,760 yards. The statute mile was standardised between the Commonwealth of Nations and the United States by an international agreement in 1959, when the yard was formally redefined with respect to SI units as 0.9144, making the mile exactly (). For everyday use, five miles equates roughly to eight kilometres.
With qualifiers, mile is also used to describe or translate a wide range of units derived from or roughly equivalent to the Roman mile (roughly ), such as the nautical mile (now exactly), the Italian mile (roughly ), and the Chinese mile (now exactly). The Romans divided their mile into 5,000 pedes (), but the greater importance of furlongs in the Elizabethan-era England meant that the statute mile was made equivalent to or in 1593. This form of the mile then spread across the British Empire, some successor states of which continue to employ the mile. The US Geological Survey now employs the metre for official purposes, but legacy data from its 1927 geodetic datum has meant that a separate US survey mile continues to see some use, although it was officially phased out in 2022. While most countries replaced the mile with the kilometre when switching to the International System of Units (SI), the international mile continues to be used in some countries, such as the United Kingdom, the United States, and a number of countries with fewer than one million inhabitants, most of which are UK or US territories or have close historical ties with the UK or US.
The present international mile is usually what is understood by the unqualified term mile. When this distance needs to be distinguished from the nautical mile, the international mile may also be described as a land mile or statute mile. In British English, statute mile may refer to the present international mile or to any other form of English mile since the 1593 Act of Parliament, which set it as a distance of . Under American law, however, statute mile refers to the US survey mile. Foreign and historical units translated into English as miles usually employ a qualifier to describe the kind of mile being used but this may be omitted if it is obvious from the context, such as a discussion of the 2nd-century Antonine Itinerary describing its distances in terms of miles rather than Roman miles.
In modern times, Agrippa's Imperial Roman mile was empirically estimated to have been about in length, slightly less than the of the modern international mile.
In Hellenic areas of the Empire, the Roman mile (, mílion) was used beside the native Greek units as equivalent to 8 stadia of 600 Greek feet. The mílion continued to be used as a Byzantine unit and was also used as the name of the zero mile marker for the Byzantine Empire, the Milion, located at the head of the Mese near Hagia Sophia.
The Roman mile spread throughout Europe, with its local variations giving rise to the different units. Also arising from the Roman mile is the milestone. All roads radiated out from the Roman Forum throughout the Empire – 50,000 (Roman) miles of stone-paved roads. At every mile was placed a shaped stone. Originally, these were obelisks made from granite, marble, or whatever local stone was available. On these was carved a Roman numeral, indicating the number of miles from the centre of Rome – the Forum. Hence, one can know how far one is from Rome.
The origins of English units are "extremely vague and uncertain", but seem to have been a combination of the Roman system with native and Germanic systems both derived from multiples of the barleycorn. Probably by the reign of Edgar in the 10th century, the nominal prototype physical standard of English length was an arm-length iron bar (a yardstick) held by the king at Winchester; the foot was then one-third of its length. Henry I was said to have made a new standard in 1101 based on his own arm. Following the issuance of Magna Carta in 1215, the barons of Parliament directed John Lackland and his son to keep the king's standard measure (Mensura Domini Regis) and Troy pound at the Exchequer, which thereafter verified local standards until its abolition in the 19th century. New brass standards are known to have been constructed under Henry VII and Elizabeth I.
Arnold's Customs of London recorded a mile shorter than previous ones, coming to 0.947 international miles (5,000 feet) or 1.524 km.
Before the Renaissance, there were various regional miles in Scandinavia. In Sweden, the regional miles were eventually divided after province, so called landskapsmil (roughly "county miles"). snl.no Old Swedish Units of Measurement - Linear Measure Suureet ja yksiköt. SI-mittayksikköjärjestelmäQuantities and units. The International System of Units (SI) Some noteworthy Swedish county miles are:
While Denmark eventually adopted the Prussian mile (see ), the Swedish kept their indigenous miles. In 1649 the Swedish government made the Uppland mile the de facto Swedish mile, or "unit mile" (enhetsmil), for all of Sweden, also called the "land mile" or "long mile". In Finland, then part of Sweden, their measurement peninkulma (which is translated as "mile") then became equivelant to the Swedish "unit mile", which later carried over when Finland seceded to the Russian Empire in 1809. When Norway became part of Sweden in 1814, forming the Union between Sweden and Norway, the Swedish standard for defining a "unit mile", 36,000 feet, was introduced to Norway, which, due to the Norwegian foot being slightly longer than the Swedish foot, then became slightly longer than in Sweden, making the "unit mile" in Norway.
Upon metrification, Finland, Norway, and Sweden, decided to redefine their miles as , since they were all based on the old Swedish "unit mile", already close to the measurent. The modern Scandinavian (metric) mile is still a unit of length common in Norway and Sweden, to a lesser extent in Finland, but not Denmark.
The Scandinavians also had their own "nautical mile", called "sea mile" (, , ), or the equivelant "sea-peninkulma" in Finnish (), equivelant to the German geographical mile ( degrees of latitude), around ; later, during metrification, standardized as .
The difference from the previous standards was 2 ppm, or about 3.2 millimetres ( inch) per mile. The US standard was slightly longer and the old Imperial standards had been slightly shorter than the international mile. When the international mile was introduced in English-speaking countries, the basic geodetic datum in America was the North American Datum of 1927 (NAD27). This had been constructed by triangulation based on the definition of the foot in the Mendenhall Order of 1893, with 1 foot = (≈0.304800609601) metres and the definition was retained for data derived from NAD27, but renamed the US survey foot to distinguish it from the international foot.When reading the document it helps to bear in mind that 999,998 = 3,937 × 254. Thus a survey mile = × 5280 (≈1609.347218694) metres. An international mile = 1609.344 / ( × 5280) (=0.999998) survey miles.
The exact length of the land mile varied slightly among English-speaking countries until the international yard and pound agreement in 1959 established the yard as exactly 0.9144 metres, giving a mile of exactly 1,609.344 metres. The US adopted this international mile for most purposes, but retained the pre-1959 mile for some land-survey data, terming it the U. S. survey mile. In the United States, statute mile normally refers to the survey mile, Convert mile [statute] to mile [statute, US] "1 metre is equal to mile statute, or mile statute,. ... The U.S. statute mile (or survey mile) is defined by the survey foot. This is different from the international statute mile, which is defined as exactly 1609.344 metres. The U.S. statute mile is defined as 5,280 U.S. survey feet, which is around metres." about 3.219 mm ( inch) longer than the international mile (the international mile is exactly 0.0002% less than the US survey mile).
While many countries abandoned the mile when switching to the metric system, the international mile continues to be used in some countries, such as Liberia, Myanmar,Naypyitaw Tollbooth.jpg the United Kingdom and the United States. Maximum posted speed limits (US) IIHS. Retrieved 14 September 2011 It is also used in a number of territories with less than a million inhabitants, most of which are UK or US territories, or have close historical ties with the UK or US: American Samoa, Bahamas, Belize, British Virgin Islands, Cayman Islands, Dominica, Falkland Islands, Grenada, Guam, The N. Mariana Islands, Samoa, St. Lucia, St. Vincent & The Grenadines, St. Helena, St. Kitts & Nevis, the Turks & Caicos Islands, and the US Virgin Islands. The mile is even encountered in Canada, though this is predominantly in rail transport and horse racing, as the roadways have been metricated since 1977.Act current to 18 January 2012. Canadian units (5) The Canadian units of measurement are as set out and defined in Schedule II, and the symbols and abbreviations therefor are as added pursuant to subparagraph 6(1)(b)(ii). Weights and Measures Act February 2012, Rail Report – 2010 – Report Number R10E0096. Other Factual Information (See Figure 1). 2. Assignment 602 travelled approximately 12 car lengths into track VC-64 and at a speed of 9 mph struck a stationary cut of 46 empty cars (with the air brakes applied) that had been placed in the track about hours earlier. Canadian railways have not been metricated and therefore continue to measure trackage in miles and speed in miles per hour. Hastings Racecourse Fact Book Like Canadian railways, Canadian race tracks have not been metricated and continue to measure distance in miles, furlongs, and yards (see page 18 of the fact book). Ireland gradually replaced miles with kilometres, including in speed measurements; the process was completed in 2005.
The United States redefined its yard in 1893, and this resulted in US and Imperial measures of distance having very slightly different lengths.
The North American Datum of 1983 (NAD83), which replaced the NAD27, is defined in metres. State Plane Coordinate Systems were then updated, but the National Geodetic Survey left individual states to decide which (if any) definition of the foot they would use. All State Plane Coordinate Systems are defined in metres, and 42 of the 50 states only use the metre-based State Plane Coordinate Systems. However, eight states also have State Plane Coordinate Systems defined in feet, seven of them in US survey feet and one in international feet.
State legislation in the US is important for determining which conversion factor from the metric datum is to be used for land surveying and real estate transactions, even though the difference (2 ppm) is hardly significant, given the precision of normal surveying measurements over short distances (usually much less than a mile). Twenty-four states have legislated that surveying measures be based on the US survey foot, eight have legislated that they be based on the international foot, and eighteen have not specified which conversion factor to use.
SPCS 83 legislation refers to state legislation that has been passed or updated using the newer 1983 NAD data. Most states have done so. Two states, Alaska and Missouri, and two jurisdictions, Guam and Puerto Rico, do not specify which foot to use. Two states, Alabama and Hawaii, and four jurisdictions, Washington, DC, US Virgin Islands, American Samoa and Northern Mariana Islands, do not have SPCS 83 legislation.
In October 2019, US National Geodetic Survey and National Institute of Standards and Technology announced their joint intent to retire the US survey foot and US survey mile, as permitted by their 1959 decision, with effect on January 1, 2023.
Since 1929 the international nautical mile is defined by the First International Extraordinary Hydrographic Conference in Monaco as exactly 1,852 metres (which is or ).. In the United States, the nautical mile was defined in the 19th century as , whereas in the United Kingdom, the Admiralty nautical mile was defined as and was about one minute of latitude in the latitudes of the south of the UK. Other nations had different definitions of the nautical mile.
The data mile is used in radar-related subjects and is equal to 6,000 feet (1.8288 kilometres). The radar mile is a unit of time (in the same way that the light year is a unit of distance), equal to the time required for a radar pulse to travel a distance of two miles (one mile each way). Thus, the radar statute mile is 10.8 μs and the radar nautical mile is 12.4 μs.
During metrification in 1875, this brought it down to about from its former equivalence of 3950 fathoms (, ) or about .
Metric mile has also been used to denote other metric measurements under the name mile, such as the Scandinavian mile (), and previously also the kilometre, in Dutch language.
The Scandinavian metric mile is based of the old Swedish "unit mile" (), which was standardised as 36,000 Swedish feet or in 1649; before that, the mile varied by province from about , also known as "county miles" (). In Finland, then part of Sweden, the traditional Finnish measurement peninkulma, or "Finnish mile" (), became redefined as equivelant to the Swedish "unit mile" , which was then kept when Finland seceded to Russia in 1809. When Norway became part of Sweden in 1814, forming the Union between Sweden and Norway, the Swedish standard for defining a mile was introduced, which then became slightly longer in Norway than in Sweden, due to the Norwegian foot being slightly longer than the Swedish foot, making the "unit mile" in Norway. Upon metrification, each country decided to redefine their mile to 10 kilometres.
In Chinese, this unit and the imperial mile are written using the same word (里), with a qualifier to distinguish between systems if needed | ||||||
Biblical and Talmudic units of measurement | ||||||
Ancient Roman units of measurement | ||||||
Over the course of time, the length of a yard changed several times and consequently so did the English, and from 1824, the imperial mile. The statute mile was introduced in 1592 during the reign of Queen Elizabeth I | ||||||
On 1 July 1959, the imperial mile was standardized to an exact length in metres. This figure corresponds to 5280 feet at 25.4 millimeters per inch. | ||||||
From 1959 also called the US Survey Mile. From then, its only utility has been land survey, before it was the standard mile. From 1893, its exact length in metres was: × 1760 | ||||||
Measured at a circumference of 40,000 km. Abbreviation: NM, nm | ||||||
Although the NM was defined on the basis of the minute, it varies from the equatorial minute, because at that time the circumference of the equator could only be estimated at 40,000 km. | ||||||
Under the reign of Emperor Septimius Severus, this replaced the Roman mile as the official unit of distance in the Gauls and Germanic peoples provinces, although there were regional and temporal variations. | ||||||
Units of measurement in France before the French Revolution | ||||||
5,000 | légua nova | Portugal | ||||
Obsolete German units of measurement | ||||||
Spanish customary units | ||||||
= 20,000 feet | ||||||
5,590 | légua | Brazil | ||||
Derived from Persian parasang | ||||||
Eclipsed by the conquest of Wales by Edward I | ||||||
6,197 | légua antiga | |||||
6,700 | Breslau mile | Silesia | 1630 | 1872 | Also known as mila wrocławska in Polish | |
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete Russian units of measurement | ||||||
German Empire, North German Confederation, Grand Duchy of Hesse, Russia. Obsolete German units of measurement | ||||||
Primarily for Denmark defined by Ole Rømer. Obsolete German units of measurement | ||||||
Austrian units of measurement | ||||||
8,534.31 | Mila | Poland | 1819 | 7146 meters before 1819, also equaled 7 verst | ||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Obsolete German units of measurement | ||||||
Still commonly used today, e.g. for road distances; equates to the myriametre | ||||||
Obsolete German units of measurement | ||||||
In normal speech, "mil" means a Scandinavian mile of 10 km. | ||||||
was equivalent to 3,000 Rhenish rods. |
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