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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 Idaho

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County or City SPCS27 Code SPCS83 Code
Ada 11103 1103
Adams 11103 1103
Bannock 11101 1101
Bear Lake 11101 1101
Benewah 11103 1103
Bingham 11101 1101
Blaine 11102 1102
Boise 11103 1103
Bonner 11103 1103
Bonneville 11101 1101
Boundary 11103 1103
Butte 11102 1102
Camas 11102 1102
Canyon 11103 1103
Caribou 11101 1101
Cassia 11102 1102
Clark 11101 1101
Clearwater 11103 1103
Custer 11102 1102
Elmore 11103 1103
Franklin 11101 1101
Fremont 11101 1101
Gem 11103 1103
Gooding 11102 1102
Idaho 11103 1103
Jefferson 11101 1101
Jerome 11102 1102
Kootenai 11103 1103
Latah 11103 1103
Lemhi 11102 1102
Lewis 11103 1103
Lincoln 11102 1102
Madison 11101 1101
Minidoka 11102 1102
Nez Perce 11103 1103
Oneida 11101 1101
Owyhee 11103 1103
Payette 11103 1103
Power 11101 1101
Shoshone 11103 1103
Teton 11101 1101
Twin Falls 11102 1102
Valley 11103 1103
Washington 11103 1103

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