Data.gov publishes 559,540 open datasets for United States. Browse them live in Vizzie and turn any one into a map or chart.
Data.gov is the open-data portal for United States. It runs on CKAN, an open catalogue standard used by many national governments. You can browse it directly at catalog.data.gov. Reuse terms are set out in the portal's terms of service (Federal works are US public domain, but harvested state/local records carry their own licences.).
Data.gov publishes one licence across its whole catalogue, so every dataset here is covered by it. That is a stronger position than an undeclared catalogue, where nothing grants permission at all — but the portal's terms are what govern, so read them before you rely on the data. Vizzie resolves each dataset to the same licence and writes the attribution line for you when you export or publish.
Metadata-only catalogue. Federal works public domain; harvested state/local records carry their own licences — read per-dataset licence, don't assume US-PD for non-federal publishers.
Data.gov doesn't expose a machine-readable breakdown of who publishes what, so there's no reliable publisher ranking to show here. Vizzie still surfaces each dataset's own publisher as you browse.
No download, no GIS specialist. Opens in Vizzie.