LEGISLATIVE BRANCH

LexisNexis Congressional Universe - This is the one stop shopping for modern legislative history indexing and documents. By license agreement, this resource is only available to Northeastern University School of Law students, faculty, and staff, from computers on the law school network.
Constitution of the United States: Analysis and Interpretation - contains an annotated Constitution of the United States and analysis of cases decided by the Supreme Court of the United States as they relate to the Constitution.
Legislative Branch Resources from GPO Access, including bills, committee reports, selected hearing transcripts, Congressional Record, and more
General Accounting Office (GAO) - the investigative arm of Congress
House Of Representatives
How Our Laws Are Made a guide to the legislative process authored by Charles W. Johnson, Parlimentarian, United States House of Representatives
LLRX's Guide to State and Federal Legislative Research - A collection of links for state and federal legislation, including Federal Links, State Links, Blogs, Research Guides, Political Info Links, and Subscription Services
LLSDC's Legislative Sourcebook - The Law Librarians' Society of Washington, D.C. provides practical how-to guides for compiling a federal legislative history, links to a table giving the status of select pieces of legislation, discusses how to get Internet and Online access to legislative documents and more.
Library of Congress (LOC)
Legislative Histories at University of Michigan Documents Center
Office of the Clerk, U.S. House of Representatives - Online Information Center
Senate
THOMAS: Legislative Information on the Internet: bills, public laws, committee reports, selected hearing transcripts, Congressional Record, and more
A Century of Lawmaking for a New Nation: U.S. Congressional Documents and Debates, 1774-1873 - from the Library of Congress
United States Code at GPO Access
United States Code at House of Representatives
United States Code at LII