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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 Alabama

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County or City SPCS27 Code SPCS83 Code
Autauga 10102 102
Baldwin 10102 102
Barbour 10101 101
Bibb 10102 102
Blount 10102 102
Bullock 10101 101
Butler 10102 102
Calhoun 10101 101
Chambers 10101 101
Cherokee 10101 101
Chilton 10102 102
Choctaw 10102 102
Clarke 10102 102
Clay 10101 101
Cleburne 10101 101
Coffee 10101 101
Colbert 10102 102
Conecuh 10102 102
Coosa 10101 101
Covington 10101 101
Crenshaw 10101 101
Cullman 10102 102
Dale 10101 101
Dallas 10102 102
DeKalb 10101 101
Elmore 10101 101
Escambia 10102 102
Etowah 10101 101
Fayette 10102 102
Franklin 10102 102
Geneva 10101 101
Greene 10102 102
Hale 10102 102
Henry 10101 101
Houston 10101 101
Jackson 10101 101
Jefferson 10102 102
Lamar 10102 102
Lauderdale 10102 102
Lawrence 10102 102
Lee 10101 101
Limestone 10102 102
Lowndes 10102 102
Macon 10101 101
Madison 10101 101
Marengo 10102 102
Marion 10102 102
Marshall 10101 101
Mobile 10102 102
Monroe 10102 102
Montgomery 10101 101
Morgan 10102 102
Perry 10102 102
Pickens 10102 102
Pike 10101 101
Randolph 10101 101
Russell 10101 101
St. Clair 10101 101
Shelby 10102 102
Sumter 10102 102
Talladega 10101 101
Tallapoosa 10101 101
Tuscaloosa 10102 102
Walker 10102 102
Washington 10102 102
Wilcox 10102 102
Winston 10102 102

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