NHGIS (National Historical Geographic Information System) at the University of Minnesota features aggregate census data covering over two centuries (1790 to 2000). The site includes access to shape files that can be used to map the data.
Social Explorer from the City University of New York, provides "easy access to demographic information about the United States, from 1940 to 2010." Maps and reports. This is a subscription service which is not cheap. They offer a 30-day free trial version.
This file last modified Tuesday September 06, 2011, 10:32:37