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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 Montana

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

County or City SPCS27 Code SPCS83 Code
Beaverhead 12503 2500
Big Horn 12503 2500
Blaine 12501 2500
Broadwater 12503 2500
Carbon 12503 2500
Carter 12503 2500
Cascade 12502 2500
Chouteau 12501 2500
Custer 12503 2500
Daniels 12501 2500
Dawson 12502 2500
Deer Lodge 12503 2500
Fallon 12503 2500
Fergus 12502 2500
Flathead 12501 2500
Gallatin 12503 2500
Garfield 12502 2500
Glacier 12501 2500
Golden Valley 12503 2500
Granite 12503 2500
Hill 12501 2500
Jefferson 12503 2500
Judith Basin 12502 2500
Lake 12502 2500
Lewis and Clark 12502 2500
Liberty 12501 2500
Lincoln 12501 2500
McCone 12502 2500
Madison 12503 2500
Meagher 12502 2500
Mineral 12502 2500
Missoula 12502 2500
Musselshell 12503 2500
Park 12503 2500
Petroleum 12502 2500
Phillips 12501 2500
Pondera 12501 2500
Powder River 12503 2500
Powell 12502 2500
Prairie 12502 2500
Ravalli 12503 2500
Richland 12502 2500
Roosevelt 12501 2500
Rosebud 12503 2500
Sanders 12502 2500
Sheridan 12501 2500
Silver Bow 12503 2500
Stillwater 12503 2500
Sweet Grass 12503 2500
Teton 12501 2500
Toole 12501 2500
Treasure 12503 2500
Valley 12501 2500
Wheatland 12503 2500
Wibaux 12502 2500
Yellowstone 12503 2500

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