US DATA SPECIFICALLY

Geospatial One Stop - federal, state & local maps & data
     part of National Spatial Data Infrastructure which includes state data clearinghouses
Data Sites for the Individual States (Dartmouth)
The National Atlas - minimal cost to files
Clearinghouse from the Federal Geographic Data Committee - 250 spatial data servers
State GIS Clearinghouse Data Sites (MIT) - Includes multiple sites for most states with
     subject specific data
USGS Geospatial Data Clearinghouse - Spatial data of all types from the USGS and other
     government agencies
TerraServer USA - USGS aerial imagery and USGS topographic maps which you can integrate;
     images of famous places or search for images of a town
U.S. Census Bureau - American Factfinder - Demographic data in map and/or table form
U.S. Census 2000 Map Server - Binghamton University, NY. After choosing your Census Category and
     Census Geography, click the Classify Layers tool to choose and map a statistic.
USGS Digital Elevation Model (DEM) data files
USGS Geography Products - Digital Data
Water Resources of the US - USGS, selected data for 1.5 million sites from 1857+
National Geophysical Data Center - data for land, marine, satellite, snow & ice, & solar-terrestrial
National Park Service Interactive Map Center - national parks
GeoMAC Wildfire Viewer - GeoMAC Team (Dept. of Interior's fire management agencies) mapping
     wildfire activity
GEODE (Geo-Data Explorer) - data produced by USGS & other government agencies