"As one of the cornerstones of the U.S. Geological Survey's (USGS) National Geospatial Program, The National Map is a collaborative effort among the USGS and other Federal, State, and local partners to improve and deliver topographic information for the Nation. It has many uses ranging from recreation to scientific analysis to emergency response. "

"The National Map." National Geospatial Program, U. S. Department of the Interior, www.usgs.gov/core-science-systems/national-geospatial-program/national-map. Accessed 14 Oct. 2019.