A mile is a unit of length, usually used to measure distance, in a number of different systems, including Imperial units, United States customary units and Norwegian/Swedish mil. Its size can vary from system to system, but in each is between one and fifteen kilometers. In contemporary English contexts, mile most commonly refers to the international mile of 5,280 feet, 1,760 yards, or exactly 1,609.344 meters. However it can also refer to either of the following for specific uses:
There have been several abbreviations for mile (with and without trailing period): mi, ml, m, M. In the United States, the National Institute of Standards and Technology now uses and recommends mi but in everyday usage (at least in the United States and in the United Kingdom) usages such as miles per hour and miles per gallon are almost always abbreviated as mph or mpg (rather than mi/h or mi/gal).
The formula "multiply by 8 and divide by 5" to convert international miles to kilometers gives a conversion of 1.6, accurate to 0.6%, which is a useful approximation.
The current definition of a mile as 5,280 feet (as opposed to 5,000) dates to the 13th century, and was confirmed by statute in the reign of Queen Elizabeth I; However, various English-speaking countries maintained independent length standards for the yard, which differed by small but measurable amounts, and thus led to miles of slightly different lengths. This was resolved in 1959 with the definition of the current international mile by Australia, Canada, New Zealand, South Africa, the United Kingdom, and the United States.
It is also asserted that the Persians came up with the mile, as they lined their roads with a large post called a mile, pronounced [mile] "mee-le".
The international mile (and before 1959, the statute mile) is the distance typically meant when the word mile is used without other qualifying words (e.g. nautical mile, see below). The international and statute miles are both equal to 5,280 feet, but the international mile is defined in terms of the international foot (0.3048 m), while the statute miles of the various English-speaking countries were based on the national foot of each country. The (mostly obsolete) U.S. statute mile is based on the U.S. survey foot (which is exactly 1200/3937 m) and differs from the international mile by about 3 mm.
The name statute mile originates from a statute of the Parliament of England in 1592 during the reign of Elizabeth I. This defined the statute mile as 5,280 ft or 1,760 yards; or 63,360 inches. Both statute and international miles are divided into eight furlongs (the length generally that a furrow was ploughed before the horses were turned, furlong = furrow-long). In turn a furlong is ten chains (a surveyor's chain, used as such until laser range finders took over); a chain is 22 yards and a yard is three feet, making up 5,280 ft.
The nautical mile was originally defined as one minute of arc along a meridian of the Earth. It is a convenient reference since it is fairly constant at all latitudes, in contrast with degrees of longitude which vary from from 1 NM at the equator to zero at the poles.
Navigators use dividers to step off the distance between two points on the navigational chart, then place the open dividers against the minutes-of-latitude scale at the edge of the chart, and read off the distance in nautical miles. Since it is now known that the Earth is not perfectly spherical but an oblate spheroid, the length derived from this method varies slightly from the equator to the poles. For instance, using the WGS84 Ellipsoid, the commonly accepted Earth model for many purposes today, one minute of latitude at the WGS84 equator is 6,087 feet and at the poles is 6,067 feet. On average it is about 6,076 feet (about 1852 meters or 1.15 statute miles).
In the United States of America, the nautical mile was defined in the nineteenth century as 6,080.2 feet (1,853.249 m), whereas in the United Kingdom the Admiralty nautical mile was defined as 6,080 feet (1,853.184 m) and was approximately one minute of latitude in the latitudes of the south of the UK. Other nations had different definitions of the nautical mile, but it is now internationally defined to be exactly 1,852 meters.
The nautical mile per hour is known as the knot. Nautical miles and knots are almost universally used for aeronautical and maritime navigation because of their relationship with degrees and minutes of latitude and the convenience of using the latitude scale on a map for distance measuring.
COUNTRY MILE[STONE]; This year's Woodbury Days celebration features the 30th running of the Country Mile.(NEWS)
Aug 21, 2011; Byline: TIM HARLOW; STAFF WRITER When the starting gun goes off at 7 a.m. next Sunday, as many as 1,000 runners competing in the...
Justices scold Warren school board; Appeals court rules that former superintendent's due-process rights were violated 'by a country mile' when he was fired
Nov 20, 2004; A federal appeals court has ruled that a Jo Daviess County, Ill., school board's effort to provide a former school superintendent...