US Survey Mile (mi (US))

US land surveyHistorical unit (no longer in standard use)

5,280 US survey feet (about 1,609.347 m). Slightly longer than the international mile, used in US land surveys until 2022.

1 US survey mile = 1,609.347219 meters (approximately).

About the US survey mile

Because it is built from 5,280 survey feet, this mile inherits the survey foot's tiny excess and comes to about 1,609.347 m, against exactly 1,609.344 m for the international mile. The gap is under 1/8 inch, or 3.2 mm, per mile, and one international mile equals 0.999998 survey miles. In US law the formal statute mile was the survey mile, though everyday usage treats the two as the same.

Over a single trip the difference vanishes, but State Plane Coordinate Systems can stretch across hundreds of miles, where a few millimetres per mile accumulate into something a surveyor must account for. For that reason surveyors kept the survey mile long after the international foot took over elsewhere. In October 2019 the National Geodetic Survey and NIST announced that the survey foot and mile would be retired from 1 January 2023, and NIST says the unit now survives only for historic and legacy data. Maps and deeds written before then still use it.

Sources: Wikipedia: Mile; NIST: U.S. survey foot

US Survey Mile conversion chart

1 US survey mile expressed in every other length unit:

More US land survey units

• US survey foot (length)
• US survey acre (area)
• section (area)
• township (area)

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