NGS precise positioning programs span the era of line-of-sight observations to modern satellite positioning techniques.

Geodesy is the science of determining the size and shape of the Earth and the location of points upon its surface. The National Geodetic Survey (NGS) develops and maintains a national system of positioning data needed for transportation, navigation, and communication systems; land record systems; mapping and charting efforts; and defense operations. The centerpiece of this system is the National Spatial Reference System (NSRS). This is a national coordinate system that defines position (latitude, longitude and elevation), distances and directions between points, strength of gravitational pull, and how these change over time. NSRS includes:

• a network of precisely located, permanently marked, in-ground geodetic reference points;
• a national set of Global Positioning System (GPS) Continuously Operating Reference Stations (CORS), which help users assess and refine the reliability of GPS data;
• a national shoreline based on long-term water-level observations, which aids accurate modeling of storm surge, coastal flooding, and pollution movements; and
• a set of models that predict geophysical processes such as land subsidence (sinking) and uplift, movement of the Earth’s crust, and other phenomena affecting spatial measurements.

A national spatial reference system helps prevent these kinds of misalignments by providing spatial accuracy for locating transportation, communication, and navigation systems.

NGS also implements a coastal mapping program, which measures precise positions of the shoreline and other features needed for creating accurate nautical charts. It conducts aerial photography surveys near airports in the United States and its territories to locate obstructions and aids to air travel. NGS also develops industry specifications and standards for conducting geodetic surveys, coordinates the development and application of new surveying instrumentation and procedures, and assists state, county, and municipal agencies through a variety of cooperative programs and training workshops.

Curious readers may wonder why NGS is part of NOAA’s National Ocean Service (NOS). NGS traces its roots to the Survey of the Coast, the nation's first civilian scientific agency, established by President Thomas Jefferson in 1807. Its mission soon included surveys of the interior as the nation grew westward. In 1878, the agency was reorganized and given a new name, the Coast and Geodetic Survey, which it maintained until 1970.

Disks like this are implanted by the National Geodetic Survey throughout the U.S. to mark precise positions.

In 1970, the National Oceanic and Atmospheric Administration (NOAA) was created and NOS was established as a line office of NOAA. To acknowledge the geodetic portion of NOAA’s mission, the part of NOS responsible for geodetic functions was named the National Geodetic Survey.