Links

American FactFinder – Contains fact sheets, static and interactive maps, data downloads for 1990 and 2000, and extensive documentation - https://factfinder.census.gov
Census 2000 Summary File 1 (SF1) - http://www.census.gov/census2000/sumfile1.html
Census 2000 Summary File 3 (SF3) - http://www.census.gov/census2000/sumfile3.html
Census 2010 Summary File 1 (SF1) - https://www.census.gov/mp/www/cat/decennial_census_2010/summary_file_1_1.html
TIGER/Line Shapefiles and TIGER/Line Files - https://www.census.gov/geo/maps-data/data/tiger-line.html

National Historical Geographic Information System (Minnesota Population Center, University of Minnesota) – Project to create and disseminate census information back to 1790 - http://www.nhgis.org

CensusScope (Social Science Data Analysis Network at the Population Studies Center, University of Michigan) - Contains web tools for investigating U.S. demographic trends - http://www.censusscope.org
Lewis Mumford Center for Comparative Urban and Regional Research (University at Albany, SUNY) - Metropolitan racial and ethnic change - Census 2000 - http://mumford.albany.edu/census
Social Explorer (Queens College of the City University of New York) – Interactive maps for the entire U.S. Census, 1790 through 2010 and the American Community Survey, 2005 through 2014 - http://www.socialexplorer.com
MABLE/Geocorr (Missouri Census Data Center) - Geographic correspondence engine with Census 2000 geography -
http://mcdc2.missouri.edu/websas/geocorr2k.html and Census 2010 geography - http://mcdc.missouri.edu/websas/geocorr12.html

There are many regional and local projects highlighting census data in certain areas. These are some that we have found useful in our research.

New York City Department of City Planning, Population Division – Maps and analyses of New York City’s population, as well as interactive neighborhood maps - http://www1.nyc.gov/site/planning/data-maps/nyc-population.page
Greater New Orleans Community Data Center – Information on New Orleans neighborhoods and the impact of Hurricane Katrina - http://www.datacenterresearch.org/

Gridded Population of the World (GPW), version 4 – Global 30 arc-second gridded population data, based on 12,500,000 subnational census units - http://sedac.ciesin.columbia.edu/data/collection/gpw-v4
Global Rural-Urban Mapping Project (GRUMP), version 1 - Global 30 arc-second gridded population data with urban reallocation. GRUMP is comprised of 400,000 census units and urban footprints based largely on nighttime lights - http://sedac.ciesin.columbia.edu/data/collection/grump-v1
LandScan – Global 30 arc-second gridded ambient population data, based on sub-national census data apportioned to each grid cell based on proximity to roads, slope, land cover, and other information - http://www.ornl.gov/sci/landscan