This layer is a georeferenced raster image displaying elevation data for the conterminous United States. These data were derived from the National Elevation Dataset (NED) released in October, 2012, The elevation data shows the terrain at a resolution of 100 meters. The NED is a raster product assembled by the U.S. Geological Survey, designed to provide national elevation data in a seamless form with a consistent datum, elevation unit, and projection. Data corrections made in the NED assembly process minimize artifacts, permit edge matching, and fill sliver areas of missing data. The NED is updated on a bi-monthly basis. This layer is part of the 1997-2014 edition National Atlas of the United States. The 100-meter resolution elevation data were developed to portray the terrain of the United States at 1:1,000,000 scale. They are intended primarily for visual purposes. The original NED data should be used for conducting analysis and determining the most accurate elevation values. No responsibility is assumed by the National Atlas of the United States in the use of these data. National Atlas of the United States. (2012). 100-Meter Resolution Elevation of the Conterminous United States. National Atlas of the United States. Available at: http://purl.stanford.edu/zz186ss2071. National Atlas of the United States. (2012). 100-Meter Resolution Elevation of the Conterminous United States. National Atlas of the United States. Available at: http://purl.stanford.edu/zz186ss2071. Included with the GeoTIFF are an auxiliary information file (.aux.xml), an image overview file (.ovr), a value attribute database file (.vat.dbf), a .tfw file (more information included below), and a .prj file (more information included below.) The contents of the associated world file (.tfw) are: >100.0 >0.0 >0.0 >-100.0 >-2539950.0 >3257950.0 The projection (.prj) file contains the following information: >PROJCS["Albers_NAD83_L48", >GEOGCS["GCS_North_American_1983", >DATUM["D_North_American_1983", >SPHEROID["GRS_1980",6378137.0,298.257222101]], >PRIMEM["Greenwich",0.0], >UNIT["Degree",0.0174532925199433]], >PROJECTION["Albers"], >PARAMETER["False_Easting",0.0], >PARAMETER["False_Northing",0.0], >PARAMETER["Central_Meridian",-96.0], >PARAMETER["Standard_Parallel_1",29.5], >PARAMETER["Standard_Parallel_2",45.5], >PARAMETER["Latitude_Of_Origin",23.0], >UNIT["Meter",1.0]] Data set extent in meters (Albers Equal-Area Conic projection) >North 3258000 >West -2540000 >East 2441000 >South 119000 There are no NULL or NODATA values in the GeoTIFF. Instead, all elevation values in oceans have been set to zero as part of the masking process. A copy of the land/water mask used in processing is available on request. Information about National Atlas Web services can be found on the Web Map and Web Feature Services page; see <http://nationalatlas.gov/infodocs/webservices.html>. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.