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Every official latitude, longitude and height published in the United States is going to change, by as much as four meters. The ground being described will not have moved at all. What is being replaced is the reference system those numbers are counted from.
The National Geodetic Survey is retiring the North American Datum of 1983 and the North American Vertical Datum of 1988. Those are the horizontal and vertical reference systems that currently underpin surveying, flood mapping, construction and aviation across the country. In their place will come four new terrestrial reference frames and one new geopotential datum. The agency has kept the national reference system since its predecessor, the Survey of the Coast, was founded in 1807.
. . . NGS gives several reasons for the change, among them alignment with international standards and with satellite systems that orbit the Earth’s center. Two of the reasons are systematic errors built into systems that were defined before satellite positioning was routine.
The first is horizontal. NAD 83 was fixed when the center of the Earth could not be located with the precision satellites later supplied, and its origin does not sit where the center of the Earth is now understood to be. The agency’s summary puts the misalignment at about 2.2 meters.
- Wikipedia: U.S. National Geodetic Survey.
