2014. Geological Survey (U.S.). This line shapefile shows elevation contour lines for the conterminous United States. The map layer was derived from the 100-meter resolution eleva... National Atlas of the United States.
2004. Instituto Nacional de Estadística, Geografía e Informática (Mexico), Canada Centre for Mapping, and Geological Survey (U.S.). This polygon shapefile contains bathymetric data with depth in metres for ocean areas covered by the extent of the North American Atlas project. Is... Canada Centre for Mapping.