The ground in the United States is not moving, but millions of official coordinates soon could. Latitude, longitude and elevation readings used by surveyors, engineers, builders and government agencies are set for a major overhaul in the US, reports Space Daily. The National Geodetic Survey (NGS) is replacing the North American Datum of 1983 (NAD 83) and the North American Vertical Datum of 1988 (NAVD 88), two systems that have been used for decades to describe where places are and how high they sit. Under the new system, some coordinates could differ from today's published figures by as much as four metres. That does not mean homes, roads or mountains are suddenly shifting. Instead, the reference system used to measure them is changing.
