Directory of Map Projections

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bipolar oblique conic conformal




Meridians: Unequally spaced curved lines, except for two straight meridians from the transformed poles to the nearest geographic pole.
Parallels: Unequally spaced curved lines.
Poles: Points.
Symmetry: None.


True along four circular arcs joined to form two S curves. These arcs do not follow any parallel or meridian. Scale is constant along circular arcs centered on each transformed pole for part of the map. The pole for most of North America is in the North Atlantic, and that for South America is in the South Pacific.


Low throughout North and South America. None along the lines of true scale and constant along circular arcs centered on the transformed pole for the given part of the map. Slight nonconformality near the line joining the two transformed poles.


Designed specifically for a low-error map of North and South America constructed by the American Geographical Society. Other organizations, including the U.S. Geological Survey, have used the American Geographical Society map as a base for maps of North or South America alone, but, since the advent of computer plotting, other projections are preferable and practical for regional maps.


Presented by Osborn Maitland Miller (1897–1979) and William A. Briesemeister of the American Geographical Society in 1941.

Description adapted from J.P. Snyder and P.M. Voxland, An Album of Map Projections, U.S. Geological Survey Professional Paper 1453. United States Government Printing Office: 1989.