North American Datum

[1] NAD 83, along with NAVD 88, is set to be replaced with a new GPS- and gravimetric geoid model-based geometric reference frame and geopotential datum, potentially in 2025.

[5][6][7][8] The datum declares the Meades Ranch Triangulation Station in Osborne County, Kansas to be 39°13′26.686″ north latitude, 98°32′30.506″ west longitude.

The latitude and longitude of every other point in North America is then based on its distance and direction from Meades Ranch: If a point was X meters in azimuth Y degrees from Meades Ranch, measured on the Clarke Ellipsoid of 1866, then its latitude and longitude on that ellipsoid were defined and could be calculated.

While ensuring the most accuracy locally, this practice makes integrating and disseminating information across regions troublesome.

As satellite geodesy and remote sensing technology reached high precision and were made available for civilian applications, it became feasible to acquire information referred to a single global ellipsoid.

[12] The practical impact is that if you use a modern GPS device set to work in NAD 83 or WGS 84 to navigate to NAD 27 coordinates (as from a topo map) near Seattle, you would be off by about 95 meters (not far enough west), and you'd be about 47 meters off near Miami (not far enough north-northeast), whereas you would be much closer for points near Chicago.

Hawaii and the coastal portions of central and southern California west of the San Andreas Fault are not on the North American Plate, so their divergence rate differs.

[2][16] The new gravimetric geoid model is the product of the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project.

These new reference frames are intended to be easier to access and to maintain than NAD 83 and NAVD 88, which rely on physical survey marks that deteriorate over time.