ESRI Data & Maps Provides basic spatial data such as internal political boundaries, population, railroads, rivers, water bodies, and more.
TIGER/Line Files The TIGER/Line files are a digital database of geographic features, such as roads, railroads, rivers, lakes, political boundaries, census statistical boundaries, etc. covering the entire United States. The data base contains information about these features such as their location in latitude and longitude, the name, the type of feature, address ranges for most streets, the geographic relationship to other features, and other related information. They are the public product created from the Census Bureau's TIGER (Topologically Integrated Geographic Encoding and Referencing) data base of geographic information. Available in the GIS room but you can also download these from the Census Bureau.