A unit of length used in navigation by United States’ ships, before 1954, = 1,853.248 meters (about 6,080.20 feet), in concept the length of a minute of arc measured at 48°N latitude. Other sources state it is a minute of arc on the Clarke spheroid of 1866.¹
After July 1, 1954, by an agreement between the Departments of Commerce and Defense, the international nautical mile has been used.² (In the Departments’ announcements, the figure 6,076.10333... feet is given as equivalent to 1852 meters. It differs from the currently correct figure, 6,076.1159 feet, because the announcement was made prior to the change to the international foot.)
1. U.S. Dept. of Commerce. National Bureau of Standards.
Louis V. Judson.
Weights and Measures Standards of the United States. A Brief History.
Miscellaneous Publication 247.
Washington, D.C.: U. S. Government Printing Office, October 1963.
2. National Bureau of Standards.
Adoption of international nautical mile.
National Bureau of Standards Technical News Bulletin 38.
Washington, D.C.: U. S. Government Printing Office, 1954.
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Last revised: 3 October 2004.