Explains how the NHD specifies point locations within streams by using a code to indicate the reach (including the hydrologic unit) and a measure, which indicates how far the point is from the downstream end of the reach.
Links to standards prepared under the National Mapping Program to produce and maintain top quality mapping and geospatial data products. Documents may be viewed and downloaded in PDF and HTML formats with links to related information.
USGS Archive for preservation and access for satellite remote sensing data and imagery (Landsat and AVHRR). Links to locating and ordering imagery, international collaborators, advisory committee, and Earthshots (satellite photos.).
Portal to general information on the National Atlas of the United States with access for producing specialized maps and links to thematic maps including interactive maps, multimedia maps, map layers data warehouse, wall maps, and printable maps.
Shows where current natural hazard events are occurring within the US or worldwide, with information about the geographic extent of the hazard, the US agency engaged to work on it, and how long the hazard is expected be active.
Information on the Gap Analysis Program in Ohio, a geographic approach to planning for biological diversity by mapping native aquatic and terrestrial animal species and natural communities on present-day conservation lands.