North American Datum
series of geodesic datums in 1901, 1923, and 1983 versions
The North American Datum (NAD) is the horizontal datum used to define latitude and longitude (horizontal coordinates) in North America. A datum is a formal description of the shape of the Earth along with survey markers serving as "anchor" points for the coordinate system. In surveying, cartography, and land-use planning, two North American Datums are in use: the North American Datum of 1927 (NAD 27) and the North American Datum of 1983 (NAD 83). Both are geodetic reference systems based on slightly different assumptions and measurements.
Vertical measurements, based on distances above or below Mean High Water (MHW), are calculated using the North American Vertical Datum of 1988 (NAVD 88).
NAD 83, along with NAVD 88, is scheduled to be replaced in 2026 with the Datum of 2022, a new geometric reference frame and geopotential datum based on GPS and gravimetric geoid model.
First North American Datum of 1901
In 1901 the United States Coast and Geodetic Survey adopted a national horizontal datum called the United States Standard Datum, based on the Clarke Ellipsoid of 1866. It was fitted to data previously collected for regional datums, which by that time had begun to overlap. In 1913, Canada and Mexico adopted that datum, so it was also renamed the North American Datum.
North American Datum of 1927
As more data were gathered, discrepancies appeared, so the datum was recomputed in 1927, using the same spheroid and origin as its predecessor.
This brief starts where responsible research should: with the source description of “North American Datum” as series of geodesic datums in 1901, 1923, and 1983 versions. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the general reference register because the source frames it as series of geodesic datums in 1901, 1923, and 1983 versions. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Apr 8, 2026. The linked authority identifier is Q993433. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1927, 1983, 1988 and 2026.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “North American Datum” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.