Catalog of U.S. Government Publications from the U.S. Government Publishing Office 
Compilation of Presidential Documents (1993-present)
Congress.gov Legislation Search
EveryCRSReport.com publishes "reports by ... the Congressional Research Service, which provides insight and non-partisan analysis of issues of public debate."
Military and Government Collection database (requires your CCC login for access)
Supreme Court of the United States: Opinions, press releases, journals, transcripts, and more
U.S. Government Accountability Office - Browse by topic
Search for U.S. Government Publications in the Statewide Illinois Library Catalog (requires your CCC login for access)
The National Agricultural Library, under the United States Department of Agriculture, contains a wide range of information. Topics include nutrient data for foods, obesity prevention, invasive species, climate change, archival materials, and much more.
The Congressional Budget Office (CBO) is a non-partisan agency which provides Congress with independent analysis of budget and economic issues for decision making. 
ERIC, from the U.S. Department of Education, contains reports and studies from the Educational Research Information Center (requires your CCC login for access).
The National Center for Education Statistics provides searchable data sets and tools for researching aspects of education in the U.S., and internationally.
PubMed "comprises more than 28 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites."
The National Geologic Map Database contains "geoscience information for the nation," held in maps, charts, and other documents and data. OSTI.GOV is the search tool for information on science, technology, and engineering research and development funded by the U.S. Department of Energy Office, provided through the DOE's Office of Scientific and Technical Information.
The National Transportation Library provides full-text research, reports, and datasets collected by the U.S. Department of Transportation Bureau of Transportation Statistics.
