Data.gov is the official open data portal of the United States federal government. It does not host most data itself; instead it acts as a catalog that aggregates datasets published by federal agencies, states, counties, and cities, then points you to the authoritative source for each one.
For GIS work, the value is breadth. A single search surfaces boundary files, environmental monitoring data, transportation networks, census geographies, and agency-specific layers from across the U.S. public sector. Many entries link directly to ArcGIS Hub sites, Socrata portals, or raw file downloads in GeoJSON and Shapefile, which you can pull straight into Atlas.
