Geographic Information Systems (GIS): Web Resources

Explore geospatial data and resources, including an interactive map of submerged land information, maps of air quality across the U.S., data on water resources, and more.

The National Map’s Historical Topographic Map Collection (HTMC) provides a digital repository of USGS 1:250,000 scale and larger maps printed between 1884 and 2006.

The National Historical Geographic Information System (NHGIS) provides easy access to summary tables and time series of population, housing, agriculture, and economic data, along with GIS-compatible boundary files, for years from 1790 through the present and for all levels of U.S. census geography, including states, counties, tracts, and blocks.

This site is your entryway into the fascinating world of Maine geology.

Web Soil Survey (WSS) provides soil data and information produced by the National Cooperative Soil Survey. It is operated by the USDA Natural Resources Conservation Service (NRCS) and provides access to the largest natural resource information system in the world. NRCS has soil maps and data available online for more than 95 percent of the nation’s counties and anticipates having 100 percent in the near future. The site is updated and maintained online as the single authoritative source of soi

This is a collaboratively edited question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

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.

As an unbiased, multi-disciplinary science organization that focuses on biology, geography, geology, geospatial information, and water.

Historical topographic maps are being made available in GeoTIFF and GeoPDF formats. Users can find maps already digitized, find the status of specific maps, or peruse the digitization plan.

Provides "the framework for survey design, sample selection, data collection, tabulation, and dissemination. Geography provides meaning and context to statistical data."