This raster layer is a100-meter resolution land and water mask in (GeoTIFF format) of Puerto Rico and the U.S. Virgin Islands, with separate values for oceans and for land areas of the United States, Canada, Mexico, the Bahamas, and Cuba. This layer is part of the 1997-2014 edition of the National Atlas of the United States. This layer is part of the 1997-2014 edition of the National Atlas of the United States. This 100-meter resolution mask image is not intended to be shown as a map layer. Instead, it is a cartographic tool that may be used to identify, select, and adjust areas on other 100-meter resolution image data sets distributed by the National Atlas of the United States. U.S. Geological Survey. (2013). 100-Meter Resolution Land/Water Mask of Puerto Rico and the U.S. Virgin Islands, 2013. National Atlas of the United States. Available at: http://purl.stanford.edu/qm804ff1967. The following pixel values are used in this map layer: >100 Ocean >200 Land ? United States >250 Land ? British Virgin Islands 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 >-195950.0 >437950.0 The projection (.prj) file contains the following information: > PROJCS["Albers_NAD83_ PRVI ", >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",-66.5], >PARAMETER["Standard_Parallel_1",8.0], >PARAMETER["Standard_Parallel_2",18.0], >PARAMETER["Latitude_Of_Origin",15.0], >UNIT["Meter",1.0]] Data set extent in meters (Albers Equal-Area Conic projection) >North 438000 >West -196000 >East 286000 >South 230000 There are no NULL or NODATA values in the GeoTIFF. 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>. None. Acknowledgment of The National Atlas of the United States of America would be appreciated in products derived from these data. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.