Foot (unit)
US survey foot

In the United States, the foot was defined as 12 inches, with the inch being defined by the Mendenhall Order of 1893 via 39.37 inches = 1 m (making a US foot exactly 1200 / 3937 meters, approximately 0.304 800 61 m).

On December 31, 2022, the National Institute of Standards and Technology, the National Geodetic Survey, and the United States Department of Commerce deprecated use of the US survey foot and recommended conversion to either the meter or the international foot (0.3048 m). However, the historic relevance of the US survey foot persists, as the Federal Register notes:

The date of December 31, 2022, was selected to accompany the modernization of the National Spatial Reference System (NSRS) by NOAA 's National Geodetic Survey (NGS). The reason for associating the deprecation of the U.S. survey foot with the modernization of the NSRS is that the biggest impact of the uniform adoption of the international foot will be for users of the NSRS, due to very large coordinate values currently given in U.S. survey feet in many areas of the U.S. Impacts related to the change to international feet will be minimized if a transition occurs concurrently with others changes in the NSRS....

The difference in timelines will have no effect on users of the existing NSRS (National Spatial Reference System), because NGS (NOAA 's National Geodetic Survey) will continue to support the U.S. survey foot for components of the NSRS where it is used now and in the past. In other words, to minimize disruption in the use of U.S. survey foot for existing NSRS coordinate systems, the change will apply only to the modernized NSRS.

State legislation is also important for determining the conversion factor to be used for everyday land surveying and real estate transactions, although the difference (two parts per million) is of no practical significance given the precision of normal surveying measurements over short distances (usually much less than a mile). Out of 50 states and six other jurisdictions, 40 have legislated that surveying measures should be based on the US survey foot, six have legislated that they be made on the basis of the international foot, and ten have not specified.
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