Sage Stats (library database): includes datasets that span all 50 states and the District of Columbia, as well as all counties, cities, and metropolitan statistical areas dating back more than 20 years. Topics covered include crime, social welfare, population, education, and more. For help, see their FAQs page.
Detroit Crime Viewer: Interactive crime map (currently in beta phase) that shows where and when crimes were committed. Crimes are color-coded and it displays location, arrest category, report number, and charge description of incidents that happened within city limits. Users can filter results by date and crime, crime type, and also select location by police precincts, zip codes, neighborhoods, council districts, or by searching the interactive map.
National Archive of Criminal Justice Data: includes over 2,600 curated studies and datasets. It includes several large-scale and well-known datasets, including the National Crime Victimization Survey (NCVS), the FBI's Uniform Crime Reports (UCR), and the FBI's National Incident-Based Reporting System (NIBRS). For help, see their FAQs and User Support contact page.
PEW Social and Demographic Trends: Datasets from studies of behaviors and attitudes of Americans in key realms of their lives. Includes datasets on Hispanic immigration attitudes and trends from the PEW Research Center's Hispanic Trends Project.
ICPSR (Interuniversity Consortium for Political and Social Sciences Research): The largest Behavioral and Social Science data archive in the United States. ICPSR is a unit within the University of Michigan Institute for Social Research and its office is in Ann Arbor. UM-Dearborn is one of ICPSR's 760 member institutions.