The Geographic Reference System (GRS) created resulted in a network of accurately positioned horizontal and vertical control monuments (latitude, longitude, elevation, and state plane coordinates) to be used by land surveyors, engineers, cartographers, and others who have a need to locate positions on, below, or above the surface of the earth. St. Clair County now has a usable GRS that will provide a common coordinate base for use by the county, surveyors, civil engineers, contractors, and developers. It is imperative that local surveyors have access to monuments and data on a common coordinate system. The coordinate system is the Illinois State Plane Coordinate System (ISPCS) which utilizes the North American Datum of 1983 (NAD 83).
The Federal Framework
The National Geodetic Survey (NGS) is a Federal agency responsible for the National Spatial Reference System (NSRS) throughout the United States and its territories inclusive of the Caribbean and parts of South America. Presently NGS defines and manages the NSRS which provides the foundation for transportation and communication; mapping and charting; and a multitude of scientific and engineering applications. Additionally, NGS develops Federal standards for geodetic surveys and regulates coordinate surveying methods. NGS State Geodetic Advisors are stationed in several states to work with local communities to expand surveying capabilities.