GIS Data

Provides information about the creation and boundary changes of every county in the United States, from the the 1600s to 2000s; includes downloadable shapefiles for use with GIS programs. A project of the William M. Scholl Center for Family and Community History at the Newberry Library in Chicago

Historical Congressional Boundaries by state, 1789-2012.

Same creator as the link above, but available as shapefiles

Legislative Boundaries for 2012 - present. Available from the Census Bureau

Collection of Points of Interest for many topics. Free to download

Find open datasets on everything from government, health, and science to games, and dating trends

Provides downloadable data and information related to the National Park Service

Publicly accessible public transportation data

National resource for transportation spatial data and analysis that utilizes Geographic Information Systems (GIS); includes downloadable maps and the National Transportation Atlas database

Open to the public and created by the public