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Federal
National Hydrography Dataset (NHD) - USGS National Map Downloadable Data Collection NGDA
Department of the Interior —
The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's... -
Federal
USGS US Topo Map Collection
Department of the Interior —
Layered geospatial PDF 7.5 Minute Quadrangle Map. Layers of geospatial data include orthoimagery, roads, grids, geographic names, elevation contours, hydrography,... -
Federal
Terrestrial Ecosystems - Land Surface Forms of the Conterminous United States
Department of the Interior —
The U.S. Geological Survey (USGS) has generated land surface form classes for the contiguous United States. These land surface form classes were created as part of an...