US 50 States GS50 Projection

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A conformal projection designed to show the 50 states of the United States.  Classed as an azimuthal projection because it is a modified form of the Stereographic projection.

 

Scale

 

True along an irregular line approximately encompassing the regions of the 50 states of the United States. Varies less than 2 percent from true scale throughout the 50 states and adjacent bodies of water. This is less than one-fourth the variation in scale of the best standard projections.

 

Distortion

 

Shape and scale distortion very low for the 50 state region. Greater distortion for regions away from the 50 states so that the projection is unusable outside the 50 states and immediately adjacent regions.

 

Usage

 

Maps of the 50 states of the United States, especially maps for school children that show the true relative sizes and shapes of Alaska and the lower 48 states.

 

Limitations

 

Use only for US 50 state region.

 

Origin

 

Developed by John Parr Snyder of the U.S. Geological Survey in 1982. The spherical case uses a sphere for the Earth's ellipsoid.

 

The GS50 uses tenth-order complex-algebra polynomials to modify the Stereographic projection. Conformality is precise in these cases even though finite polynomial series are used.

 

Options

 

The coefficient choices are useful only for this design of a 50-State map.   Provided in both ellipsoid and spherical form.