Databases for finding demographic data:
Data-Planet: Create custom, exportable charts with data points from the US Census, such as age, gender, income, etc.
DemographicsNow
Geographically customized demographic data reports and maps. Identify patterns and trends regarding household expenditures, market penetration and location of goods and services.
Social Explorer
Current and historical census data and demographic information: US Census, American Community Survey, religious membership, carbon emissions data, etc. Customizable maps, charts, and reports. Info
Statistical Abstract of the United States (ProQuest)
Extensive selection of statistics for the United States, with selected data for regions, divisions, states, metropolitan areas, cities, and foreign countries from reports and records of government and private agencies.
American FactFinder (free website)
Data about the United States, Puerto Rico and the Island Areas. Data comes from several censuses and surveys: American Community Survey, American Housing Survey, Annual Economic Surveys, Annual Survey of Governments, etc.