The National Map
The National Map is beginning to release a series of composite base maps in 2013 which will be replacing the older base maps. These base maps combine layers in a single cached service to offer the user the simplicity of single-service base maps with the richness of combined data sources. The first composite base map was the USGS Topo made available in November 2012. The second composite base map is the USGS ImageryOnly composite base map which became available in January 2013. The next composite base map will be the USGSImageryTopo which will be similiar to the USGS Topo with an Imagery base rather than shaded relief.
The USGS Topo base map service from The National Map is a combination of contours, shaded relief, woodland and urban tint, along with vector layers, such as geographic names, governmental unit boundaries, hydrography, structures, and transportation, to provide a composite topographic base map. Data sources are the National Atlas for small scales, and The National Map for medium to large scales.
Service URL: http://basemap.nationalmap.gov/ArcGIS/rest/services/USGSTopo/MapServer
The USGS ImageryOnly base map service from The National Map is a cached, composite map service combining the following image sources:
Service URL: http://basemap.nationalmap.gov/ArcGIS/rest/services/USGSImageryOnly/MapServer
The USGS ImageryTopo base map service from The National Map is a cached, composite map service combining the ImageryOnly base map content with a rich set of vector features. This basemap introduces new cartographic styling based on the popular US Topo product at 1:36 & 1:18k scales and adjusted for smaller scales.
Service URL: http://basemap.nationalmap.gov/ArcGIS/rest/services/USGSImageryTopo/MapServer
The National Hydrography Dataset (NHD) is a comprehensive set of digital spatial data that encodes information about naturally occurring and constructed bodies of surface water (lakes, ponds, and reservoirs), paths through which water flows (canals, ditches, streams, and rivers), and related entities such as point features (springs, wells, stream gages, and dams). The information encoded about these features includes classification and other characteristics, delineation, geographic name, position and related measures, a "reach code" through which other information can be related to the NHD, and the direction of water flow. The network of reach codes delineating water and transported material flow allows users to trace movement in upstream and downstream directions. In addition to this geographic information, the dataset contains metadata that supports the exchange of future updates and improvements to the data. The NHD is available nationwide in two seamless datasets, one based on 1:24,000-scale maps and referred to as high resolution NHD, and the other based on 1:100,000-scale maps and referred to as medium resolution NHD. Additional selected areas in the United States are available based on larger scales, such as 1:5,000-scale or greater, and referred to as local resolution NHD. The NHD supports many applications, such as making maps, geocoding observations, flow modeling, data maintenance and stewardship. For additional information, go to http://nhd.usgs.gov.
Service URL: http://basemap.nationalmap.gov/ArcGIS/rest/services/USGSHydroNHD/MapServer
The USGS Hill Shade base map from The National Map was created from the National Elevation Dataset (NED), a seamless dataset of best available raster elevation data for the conterminous United States, Alaska, Hawaii, and Territorial Islands. Derived from the NED using a hill shade technique, this base map represents a continental view showing shaded relief from USGS NED layers at resolutions of 1/3-, 1-, and 2-arc-second (in Alaska only). Shaded relief (or hill shade) function parameters are: point illumination is from the NW (azimuth = 315 degrees), and altitude of the light source is 45 degrees. Color characteristics are the result of applying a color ramp in which RGB values range from white (RGB: 255, 255, 255) to brown (RGB: 166, 150, 109). The color ramp was applied with a Stretch Type of None. Contrast and Brightness values range from 4-14%, depending on scale, for cartographic purposes. For additional information on the NED, go to http://ned.usgs.gov .
Service URL: http://basemap.nationalmap.gov/ArcGIS/rest/services/USGSShadedReliefOnly/MapServer
This service consists of ocean tints, to give the outline of the US as an empty base map for the addition of other services.
Service URL: http://services.nationalmap.gov/ArcGIS/rest/services/TNM_Blank_US/MapServer