University of Wisconsin–Madison

Wisconsin Geospatial News

The Foot is Dead! Long Live the Foot!

The National Institute of Standards and Technology (NIST) and National Geodetic Survey (NGS) have announced their final decision to deprecate use of the U.S. survey foot on December 31, 2022. This decision has been discussed in several earlier SCO articles (here, here and here).

The final determination is detailed in Federal Register Notice 85 FR 62698 published on October 5, 2020.

The Notice announces the final decision to deprecate use of the U.S. survey foot on December 31, 2022. According to the notice, beginning on January 1, 2023, “the U.S. survey foot should not be used” and will be superseded by the international foot “in all applications.”

The notice further states that, “After December 31, 2022, any data derived from or published as a result of surveying, mapping, or any other activity within the U.S. that is expressed in terms of feet should only be based on the definition of one foot being equal to 0.3048 meter (exactly).”

The date of December 31, 2022 was selected to accompany the modernization of the National Spatial Reference System (NSRS) by the NGS. However, these modernization plans have been delayed for several years, as noted in this SCO article. NGS will continue to support the U.S. survey foot where it is used now; that is, to minimize disruption, the change will apply only to the modernized NSRS. The US survey foot will be maintained in NGS products and services in legacy applications, such as the State Plane Coordinate Systems of 1983 and 1927.

The Federal Register Notice provides and extensive review of the comments solicited in response to the announcement in 2019 that the US survey foot would be deprecated. Fifty-three percent of comments were in favor of the international foot, 33 percent were in favor of the US survey foot, and 14 percent were in favor of the metric system. Only 72 responses were obtained nationally, however, perhaps because the purpose of the solicitation was to identify unforeseen issues associated with the decision to deprecate the U.S. survey foot, not to ask for comments in support of or in opposition to the planned change (since that decision had already been made).

Starting in 2023, either the term “foot” or “international foot” may be used to designate the international foot. However, the preferred term is the “foot.” Interestingly, “of the 17 public comments that expressed an opinion on the name of the foot after deprecation, 14 favored retaining international as part of the name, rather than simply calling it the foot. In all cases, the reason was to avoid confusion between the types of foot.”

Since the U.S. survey foot is identified in statute for many states (including Wisconsin), state statutes will presumably need to be updated. National organizations such as the National Society of Professional Surveyors (NSPS) have developed model language to assist.

The Notice also provides a table giving the relationships for units of measure based on the foot, and some recommendations to facilitate change.

In Wisconsin, the implications of the change to the international foot are being coordinated by the Wisconsin Spatial Reference System Task Force (WSRS2022). Visit the Task Force web page for more information.