US Geological Survey - GIS Data Download
The Topographic Maps and geographical information system (GIS) data provided in The National Map are pre-generated into downloadable products often available in multiple formats. The vector datasets include: The National Hydrography Dataset(s), Watershed Boundary Dataset, Governmental Boundary Units, Transportation, Structures, Elevation Contours and Geographic Names. Raster datasets include: Digital Elevation Models (DEMs), Orthoimagery, and Land Cover. Lidar point cloud data is also available over many areas of the US.