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The State Plane Coordinate System

The State Plane Coordinate System (SPS or SPCS) is a set of 124 geographic zones or coordinate systems designed for specific regions of the United States. Each state contains one or more state plane zones, the boundaries of which usually follow county lines. There are 110 zones in the continental US, with 10 more in Alaska, 5 in Hawaii, and one for Puerto Rico and US Virgin Islands. The system is widely used for geographic data by state and local governments. Its popularity is due to at least two factors. First, it uses a simple Cartesian coordinate system to specify locations rather than a more complex spherical coordinate system (the geographic coordinate system of latitude and longitude). By thus ignoring the curvature of the Earth, "plane surveying" methods can be used, speeding up and simplifying calculations. Second, the system is highly accurate within each zone (error less than 1:10,000). Outside a specific state plane zone accuracy rapidly declines, thus the system is not useful for regional or national mapping.

Most state plane zones are based on either a Transverse Mercator projection or a Lambert conformal conic projection. The choice between the two map projections is based on the shape of the state and its zones. States that are long in the east-west direction are typically divided into zones that are also long east-west. These zones use the Lambert conformal conic projection, because it is good at maintaining accuracy along an east-west axis. Zones that are long in the north-south direction use the Transverse Mercator projection because it is better at maintaining accuracy along a north-south axis. The panhandle of Alaska, whose maximum dimension is on a diagonal, uses an Oblique Mercator projection, which minimizes the combined error in the X and Y directions.


All State Plane zones in Wyoming

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County or City SPCS27 Code SPCS83 Code
Albany 14901 4901
Big Horn 14902 4902
Campbell 14901 4901
Carbon 14902 4902
Converse 14901 4901
Crook 14901 4901
Fremont 14903 4903
Goshen 14901 4901
Hot Springs 14903 4903
Johnson 14902 4902
Laramie 14901 4901
Lincoln 14904 4904
Natrona 14902 4902
Niobrara 14901 4901
Park 14903 4903
Platte 14901 4901
Sheridan 14902 4902
Sublette 14904 4904
Sweetwater 14903 4903
Teton 14904 4904
Uinta 14904 4904
Washakie 14902 4902
Weston 14901 4901

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