The Economic Times

US latitude, longitude and elevation are about to change by up to 4 metres: Why America is replacing its 40-year-old GPS reference system

The US is preparing to replace its decades-old latitude, longitude and elevation reference systems, NAD 83 and NAVD 88. The change could make some official coordinates differ by up to four metres, even though the land itself will not move. Heres why satellite technology, gravity measurements and tectonic plate movement are forcing a major overhaul of how America measures and maps its land.