HHS Data Council Gateway to Data and Statistics
A "web-based tool that brings together key health and human services data and statistics. It is designed to complement other government resources such as FirstGov and FedStats. The Gateway covers federal, state and local government sponsored information."

Social Science Electronic Data Library
A numeric data archive providing microdata for research into AIDS/STD, disability in the U.S., the American family, adolescent pregnancy and pregnancy prevention, aging, and maternal drug abuse, and aggregate population, social, economic data supporting geographic contextual analysis.

IPUMS
REQUIRES FREE REGISTRATION. Census microdata from historic national censuses, U.S. and worldwide. Only provides microdata data sets, with data subsetting and extraction, and documentation. Frequency distributions and crosstabulations not provided.

ICPSR
USE OF ICPSR DATA REQUIRES STATISTICAL PROCESSING SOFTWARE AND GZIP DECOMPRESSION SOFTWARE. Direct-download access to social science quantitative data sets archived by ICPSR. Subjects covered include political science, sociology, demography, history, economics, communication, international relations, gerontology, public health, criminal justice, and education. The ICPSR archive includes almost all major studies in the social sciences, including the General Social Survey and International Social Survey Program, decennial Census of Population and Housing, American National Election Study, Eurobarometer, Voter News Service exit polls, US Congressional and UN roll call votes, National Crime Victimization Survey, and public opinion polls. Special topic archives, with limited interactive tabulation and extraction capability, cover health and medical care, international education, aging, criminal justice, and substance abuse and mental health.
Holdings: 1962-present.