GIS Metadata - DNGP Geographical Information Layers - Imagery

DNGP GIS Layer MetaData Details

From the Digital NGP interface, you can select a number of different layers of information to overlay on top of your imagery or to use as a basemap. Following are brief descriptions of each of these layers.

AG CENSUS

This map layer portrays a selected set of information that was collected for the 2002 Census of Agriculture by the National Agricultural Statistics Service, U.S. Department of Agriculture. There are 25 categories of data which include information about farms, crops, livestock, values of products, and farm operator characteristics. The data is for the United States and is presented by county. This is a replacement for the May 2003 Agriculture Census of the United States - 1997 map layer.

AIRPORTS

This data set includes airports in the United States, Puerto Rico and the U.S. Virgin Islands. The data were derived from an extract of The Public-Use Airports database of the National Transportation Atlas Databases-2001 (NTAD-2001), published by the Bureau of Transportation Statistics, Department of Transportation.

AQUIFER

This map layer contains the shallowest principal aquifers of the conterminous United States, Hawaii, Puerto Rico, and the U.S. Virgin Islands, portrayed as polygons. The map layer was developed as part of the effort to produce the maps published at 1:2,500,000 in the printed series "Ground Water Atlas of the United States". The published maps contain base and cultural features not included in these data. This is a replacement for the July 1998 map layer called Principal Aquifers of the 48 Conterminous United States.

CITY

This map layer includes cities in the United States, Puerto Rico and the U.S. Virgin Islands. These cities were collected from the 1970 National Atlas of the United States. Where applicable, U.S. Census Bureau codes for named populated places were associated with each name to allow additional information to be attached. The Geographic Names Information System (GNIS) was also used as a source for additional information. This is a revised version of the December 2003 map layer.

CONTINENTAL DIVIDE

This data set portrays the Continental Divide of the United States. The data set was created by extracting Hydrologic Unit Boundary line features from an existing National Atlas layer. The source data are aligned with the individual 1:2,000,000-scale Digital Line Graph (DLG) hypsography files produced by the U.S. Geological Survey.

COUNTY

This map layer portrays the State and county boundaries of the United States, Puerto Rico, and the U.S. Virgin Islands. The map layer was created by extracting county polygon features from the individual 1:2,000,000-scale State boundary Digital Line Graph (DLG) files produced by the U.S. Geological Survey. These files were then merged into a single file. This is a revised version of the November 2004 map layer.

DAM

This map layer portrays major dams of the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 79,777 dams in the U.S. Army Corps of Engineers National Inventory of Dams. This is a replacement for the April 1994 map layer.

EARTH QUAKES 1568-2004

This map layer contains the locations and attributes of significant, historic earthquakes that caused deaths, property damage, and geological effects, or were otherwise experienced by populations in the United States, Puerto Rico, and U.S. Virgin Islands. Included are earthquakes located in the United States as well as some that occurred in adjacent portions of Canada and Mexico. The main sources for the data are Seismicity of the United States, 1568-1989 and the Preliminary Determination of Epicenters for 1990 to January 2004. This is a replacement for the June 1999 map layer.

FEDERAL LANDS

This map layer consists of federally owned or administered lands of the United States, Puerto Rico, and the U.S. Virgin Islands. Only areas of 640 acres or more are included. There may be private inholdings within the boundaries of Federal lands in this map layer. This is a revised version of the January 2005 map layer.

FOREST COVER

This map layer portrays general forest cover types for the United States. Data were derived from Advanced Very High Resolution Radiometer (AVHRR) composite images recorded during the 1991 growing season, with the exception of Puerto Rico, for which Landsat Thematic Mapper (TM) data were used. A total of 25 classes of forest cover types were interpreted from the AVHRR and TM imagery aided by field observations and refined with ancillary data from digital elevation models. The data available through the National Atlas of the United States are in GeoTIFF format. This is a revised version of the May 2002 map layer, with a corrected shoreline for Greenland.

HYDROGRAPHY

A joint venture involving the National Atlas programs in Canada (Natural Resources Canada), Mexico (Instituto Nacional de Estadística Geografía e Informática), and the United States (U.S. Geological Survey), as well as the North American Commission for Environmental Co-operation, has led to the release (June 2004) of several new products: an updated paper map of North America, and its associated geospatial data sets and their metadata. These data sets are available online from each of the partner countries for download. This data has been revised and re-released in 2006.

INTERSTATE

This data set portrays the major interstates in the United States, Puerto Rico, and the U.S. Virgin Islands. The file was produced by joining the individual State roads layers from the 1:2,000,000-scale Digital Line Graph (DLG) data produced by the USGS. This is a revised version of the March 1999 data set.

LAND COVER

This map layer is GeoTIFF of 1992 land cover for the conterminous United States, at a resolution of 200 meters. The map layer was compiled by staff in the National Land Cover Characterization Program of the U.S. Geological Survey National Center for Earth Resources Observation and Science, from data produced for the 1992 National Land Cover Dataset (NLCD). The NLCD used Landsat Thematic Mapper satellite data.

NATIVE AMERICAN LANDS

This map layer shows Indian lands of the United States. Only areas of 640 acres or more are included. Federally-administered lands within a reservation are included for continuity; these may or may not be considered part of the reservation and are simply described with their feature type and the administrating Federal agency. This is an updated version of the December 2004 map layer.

PARKWAYS AND SCENIC RIVERS

This map layer portrays the linear federally-owned land features (i.e., national parkways, wild and scenic rivers, etc.) of the United States, Puerto Rico, and the U.S. Virgin Islands. The map layer was created by extracting linear federal land features from the 1:2,000,000-scale individual State DLG files produced by the U.S. Geological Survey. These files were then merged into a single map layer. This is a revised version of the July 2001 map layer.

POLITICAL BOUNDARIES

A joint venture involving the National Atlas programs in Canada (Natural Resources Canada), Mexico (Instituto Nacional de Estadística Geografía e Informática), and the United States (U.S. Geological Survey), as well as the North American Commission for Environmental Co-operation, has led to the release (June 2004) of several new products: an updated paper map of North America, and its associated geospatial data sets and their metadata. These data sets are available online from each of the partner countries both for download. This data has been revised and re-released in 2006.

POPULATED PLACES

RAILROADS

This map layer includes railroads in the conterminous United States and Alaska. This is a replacement for the December 1998 map layer.

RIVER

This map layer shows areal and linear water features of the United States, Puerto Rico, and the U.S. Virgin Islands. The original file was produced by joining the individual State hydrography layers from the 1:2,000,000-scale Digital Line Graph (DLG) data produced by the USGS. This map layer was formerly distributed as Hydrography Features of the United States. This is a revised version of the January 2003 map layer.

SHADED RELIEF

The Satellite View of the Conterminous United States, with Shaded Relief map layer is a 200-meter-resolution simulated-natural-color image of the United States. Vegetation is generally green, with forests in darker green and grasslands or shrublands in lighter green. Areas of high reflectance, including urban areas, rock, and dry bare soil, are shown in shades of pink. Very bright areas, such as snow and ice, are colored blue. The image was produced by combining Landsat Thematic Mapper (TM) imagery from the Landsat 4 and Landsat 5 satellites with relief enhanced by shading. This map layer was previously distributed as Satellite View of the Conterminous United States.

STATE

This map layer portrays the State boundaries of the United States, and the boundaries of Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting the State boundary polygons from the individual 1:2,000,000-scale State boundary Digital Line Graph (DLG) files produced by the U.S. Geological Survey. These files were then merged into a single coverage. This is an updated version of the June 2002 map layer; the date when each State was admitted to the United States was added.

STATE HIGHWAY

This data set portrays the major roads in the United States, Puerto Rico, and the U.S. Virgin Islands. The file was produced by joining the individual State roads layers from the 1:2,000,000-scale Digital Line Graph (DLG) data produced by the USGS. This is a revised version of the March 1999 data set.

TIME ZONE

This map layer portrays the time zones of the United States, Puerto Rico, and the U.S. Virgin Islands. Also included are the Greenwich Mean Time offset, and areas in the U.S. where daylight saving time is observed. This is a revised version of the June 2005 map layer.

TOWNSHIP

This map displays the townships for the six states in the UMAC region (Idaho, Montana, Wyoming, North Dakota, South Dakota and Minnesota).

UNITED STATES AVEARAGE ANNUAL PRECIPITATOIN, 1961-1990

This map layer shows polygons of average annual precipitation in the contiguous United States, for the climatological period 1961-1990. Parameter-elevation Regressions on Independent Slopes Model (PRISM) derived raster data is the underlying data set from which the polygons and vectors were created. PRISM is an analytical model that uses point data and a digital elevation model (DEM) to generate gridded estimates of annual, monthly and event-based climatic parameters.

VOLCANO

This map layer includes Holocene volcanoes, which are those thought to be active in the last 10,000 years that are within an extended area of the northern hemisphere centered on the United States. The data are a subset of data available from the Global Volcanism Program, Smithsonian Institution. This file is a replacement for the April 2004 map layer.

WATERSHED

This map layer contains hydrologic unit boundaries and codes for the United States, Puerto Rico, and the U.S. Virgin Islands. It was revised for inclusion in the National Atlas of the United States of America, and updated to match the streams file created by the USGS National Mapping Division (NMD) for the National Atlas of the United States of America. This is a revised version of the November 2002 map layer.

WILDERNESS PRESERVATION SYSTEM AREAS

These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. No responsibility is assumed by the National Atlas of the United States in the use of these data.