U.S. Census Bureau
Provides information about the U.S. population. In addition to data on populations, housing, income, etc., the “Business and Industry” link provides valuable information on the economic profiles of the U.S. There is also useful data via “Find an Area Profile with Quick Facts” (on the Census home page). Selecting “Illinois” from the drop-down menu will produce data for population, housing, and business. The site also includes the “American Fact Finder,” with community-level data.