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Posted on March 25th, 2012

The National Geodetic Survey

You may not see it, but all around you is a network that is the very foundation of modern society in the United States. No, it’s not the Internet or Facebook, this network is far more tangible and intrinsically important. It is the National Spatial Reference System (NSRS) which is maintained by the National Geodetic Survey (NGS), an office within the National Oceanic and Atmospheric Administration (NOAA). The NSRS is a “consistent coordinate system that define latitude, longitude, height, scale, gravity and orientation throughout the United States.” (NOAA)

My, my aren’t we positionally accurate! Above is a coverage map of every CORS sites in North America.

The backbone of the NSRS is the Continuously Operating Reference Stations (CORS) Program. CORS is a nationwide network of permanent GPS receivers across the US and its territories. These stations are maintained by government, academic and private institutions. This highly accurate GPS data is made available to the public by NGS to facilitate the acquisition of accurate positional coordinates relative to the NSRS. NOAA and the NGS also offer the Online Positioning User Service (OPUS), which gives the public free access to the NSRS. Users can submit coordinates collected by a survey-grade receiver through their online system and a NSRS position will be returned via email.


The NGS has been in existence for more than 200 years and was the first US scientific civilian agency. It was established by Thomas Jefferson in 1807 in order to survey and create nautical charts of the US coastline. The organization was renamed the U.S. Coast and Geodetic Survey (CGS) in 1878 as the nation and subsequently our surveying needs moved West towards the Pacific Ocean. In 1970, a number of scientific government agencies came together to create the National Oceanic and Atmospheric Administration (NOAA). The CGS was renamed the National Geodetic Survey at this time.


NGS is now an office within NOAA and maintains the NSRS. In addition to this task, the NGS makes emergency response imagery available to the public including hurricanes, tornadoes and flooding. They also continue to maintain and update the national shoreline database by creating vector layers that are derived from recent aerial and satellite imagery and LiDAR elevation data.

Katie Nelson

Geospatial Ninja

(303) 718-7163

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