Online access to Congressional Quarterly pubications: CQ Weekly & Almanac (issues in Congress); CQ Researcher (hot topics); Congress and the Nation; Historic Documents; Politics in America; and five CQ Guides: Guide to Congress; Guide to the Presidency; Guide to the U.S. Supreme Court; Guide to U.S. Elections; Guide to Political Campaigns in America.
Joint effort between UT-Austin, Penn State, U Washington funded by the NSF. The project tracks policy changes in the United States. It 'collects and organizes data from various archived sources to trace changes in the national policy agenda and public policy outcomes since the Second World War.'
Gateway to U.S. government documents which includes the Catalog of U.S. Government Publications; the Congressional Record; Congressional Bills, Laws, and Reports; Public Papers of the Presidents; and much more.
CRS is a non-partisan research service for Congress that produces highly regarded reports on legislative and policy issues at the request of Congress. Currently there is no public site with access to all reports. EveryCRSReport.com provides over 8,000 recent ones. Homeland Security Digital Library provides over 18,000 related reports. For additional sources see this list from University of Washington School of Law. Example report: Climate Change Science: Key Points.
"Non-profit institution that helps improve policy and decisionmaking through research and analysis." Focuses on health, education, national security, international affairs, law and business, the environment, and more.
Independent, federally-funded national security institution. Includes full-text of peace agreements; documents on inter- and intra-state conflicts; and documents on truth commissions (see the Library link) and links to websites on foreign affairs topics such as terrorism, human rights, peacekeeping, etc.