For more see the Government Information portal at Columbia. If you are unfamiliar with how the American Government is set up (it's confusing!) please consult this fabulous set of resources from USA.gov.
ProQuest Tools
ProQuest Congressional: This is the most comprehensive online resource available for congressional publications and legislative research. Included are: Committee Hearings, Committee Prints, Congressional Research Service (CRS) Reports, House and Senate Documents, House and Senate Reports, Senate Executive Reports, Senate Executive Treaty Documents, Legislative Histories, Statutes at Large, the Serial Set and Serial Set Maps. Most of the content is full text.
ProQuest Legislative Insight: This is a federal legislative history service that makes available thoroughly researched compilations of digital full-text publications relevant to enacted U.S. public laws. These include the full text of the public law itself, all versions of related bills, law-specific Congressional Record excerpts, committee hearings, reports, and prints. Also included are presidential signing statements, CRS reports and miscellaneous congressional publications that provide background material to aid in the understanding of issues related to the making of the law.
U.S. Government Websites
National Archives: Links and indexes to government publications in the National Archives.
Science.gov : Provide users with access to more than 200 million pages of authoritative federal science information including research and development results.
USA.gov: Official guide to government information and services