Overview

The National Geodetic Survey is a United States federal agency that defines and manages the nation’s reference framework for position and elevation. It maintains the precise coordinate system used by surveyors, mapmakers, engineers and navigators, and provides the foundational data that allow maps, charts and location services to line up across time and agencies. See the agency page: National Geodetic Survey.

Core functions and data products

The Survey establishes and preserves horizontal and vertical datums, models the shape of the Earth (the geoid), and publishes official coordinates and benchmarks. Its principal activities include:

  • Defining and publishing the national coordinate system and spatial reference frames (coordinate system).
  • Producing control points and survey marks used in mapping and engineering projects.
  • Collecting and distributing hydrographic and shoreline measurements to support mapping and coastal navigation (maps and charts).
  • Maintaining time series and models for tides and sea level (tide data), and measuring Earth’s magnetic field (magnetic surveys).

History and organization

Congress authorized the original coastal survey in 1807 to improve charts of U.S. coasts (coastal mapping). Over time the organization evolved, becoming known for much of its history as the U.S. Coast and Geodetic Survey. Since the creation of NOAA it has operated within that agency and the Department of Commerce structure (NOAA, Department of Commerce).

Tools, networks and modern programs

The Survey now combines traditional leveling and triangulation with satellite-based techniques such as GNSS to produce modern reference frames. It operates reference-station networks, provides transformation tools and models for converting between datums, and issues geoid and tide models used by engineers and scientists. These services support transportation and communication infrastructure, surveying, cartography, and a wide range of scientific and engineering uses (science and engineering).

Uses, examples and notable distinctions

Applications range from laying out highways and airports, to floodplain mapping, coastal resilience planning, maritime navigation, and integrating maps with GPS-based consumer devices. The Survey’s benchmarks and datums are the legal and technical foundation that allow disparate datasets to align precisely. For more information on its mission and products, consult the agency resources (magnetic data, tide data, agency information).

The National Geodetic Survey is a technical steward: it does not generally issue property titles, but it provides the reference framework upon which accurate land surveys and nautical charts depend.