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How are maps drawn?

To draw the Earth (or a portion of it) onto a map, map makers use different map projections that apply (or "project") the curved Earth surface onto a flat map. Although no projection will perfectly depict all areas of the Earth, different map projections make specific areas of the Earth look as accurate and realistic as possible. TOXMAP uses a map projection (called "North American Albers Equal Area Conic") which makes the continental United States look most realistic. Areas farther away from the US will appear increasingly distorted.

You can learn more about map projections from the USGS at