This poster features a portrait of Gerardus Mercator on one side and examples of the eighteen most common map projections on the other. Each example includes a description that explains the properties and uses of the projection. There are also summary tables of projection properties, general uses, and geographic areas most suitable for mapping with a given projection. The poster is viewable online and is also available as a downloadable, printable version (PDF). Hardcopies can be requested free of charge from the United States Geological Survey (USGS).