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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 Colorado

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County or City SPCS27 Code SPCS83 Code
Adams 10501 501
Alamosa 10503 503
Arapahoe 10502 502
Archuleta 10503 503
Baca 10503 503
Bent 10503 503
Boulder 10501 501
Broomfield 10501 501
Chaffee 10502 502
Cheyenne 10502 502
Clear Creek 10502 502
Conejos 10503 503
Costilla 10503 503
Crowley 10503 503
Custer 10503 503
Delta 10502 502
Denver 10502 502
Dolores 10503 503
Douglas 10502 502
Eagle 10502 502
Elbert 10502 502
El Paso 10502 502
Fremont 10502 502
Garfield 10502 502
Gilpin 10501 501
Grand 10501 501
Gunnison 10502 502
Hinsdale 10503 503
Huerfano 10503 503
Jackson 10501 501
Jefferson 10502 502
Kiowa 10503 503
Kit Carson 10502 502
Lake 10502 502
La Plata 10503 503
Larimer 10501 501
Las Animas 10503 503
Lincoln 10502 502
Logan 10501 501
Mesa 10502 502
Mineral 10503 503
Moffat 10501 501
Montezuma 10503 503
Montrose 10503 503
Morgan 10501 501
Otero 10503 503
Ouray 10503 503
Park 10502 502
Phillips 10501 501
Pitkin 10502 502
Prowers 10503 503
Pueblo 10503 503
Rio Blanco 10501 501
Rio Grande 10503 503
Routt 10501 501
Saguache 10503 503
San Juan 10503 503
San Miguel 10503 503
Sedgwick 10501 501
Summit 10502 502
Teller 10502 502
Washington 10501 501
Weld 10501 501
Yuma 10501 501

Click here to go back to the list off all State Plane grids