Data sets from the Executive branch of the U.S.

Extensive collection of maps and tools for both U.S. and international geography.

Simplified boundary files from the U.S. Census Bureau's MAF/TIGER database.

USGS science helps communities understand the implications of change, anticipate the effects of change, and reduce the risks associated with a changing environment.

Information about population, health, and the environment.

from the Natural Resources Conservation Service

sponsored by Columbia Univ.

The National Map is a collaborative effort among the USGS and other Federal, State, and local partners to improve and deliver topographic information for the Nation

U.S. data from the ICPSR (U. of Michigan)

Data for 1990, 2000, 2010.

Hydrologic and water-quality information; access to water data, publications, and maps, recent water projects and events.

NASA's Earth Observing System Data & Information System

From the Univ. of Chicago's GIS Center -- long list of international & U.S. data

Extensive collection of maps and tools for both U.S. and international geography.

Provides both historical and current Earth science data, information, and products from satellite, airborne, and surface-based instruments.

Extensive collection of maps and tools for both U.S. and international geography.

The Perry-Castañeda Library (PCL) Map Collection website is archived as of 2021 and no longer being updated

Free map-making tools from National Geographic

from the Univ. of Portsmouth (UK)

Univ. of Texas-Austin -- Perry-Castaneda collection