GIS is an integrated collection of software and data used to visualize and organize geographic data, conduct geographic analysis, and create maps and other geospatial information. Created by Frank Donnelly, Baruch College.
"Provides maps and data for ArcGIS users and the capability to find and share geographic information. The free ArcGIS Online Web application makes it easy to find content published by ESRI, ArcGIS users, and other authoritative data providers as well as upload and share content of your own."
Free downloads of national base layers, as well as other geospatial data layers. Categories include: Places, Structures, Transportation, Boundaries, Hydrography, Orthoimagery, Land Cover, and Elevation.
TIGER products are spatial extracts from the Census Bureau's MAF/TIGER database, containing features such as roads, railroads, rivers, as well as legal and statistical geographic areas. The Census Bureau offers several file types and an online mapping application.
The U.S. Cluster Mapping Project is a national economic initiative that provides open, interactive data to understand regional clusters and support business, innovation and policy in the United States.