Places to Start
This is the official catalog of U.S. government documents and publications. Entries include the Superintendent of Documents (SuDoc) class number, so you can find earlier versions of the documents in print and later documents online.
A service of the U.S. Government Publications Office that provides free electronic access to a wealth of important information products produced by the Federal government, including Congressional bills, U.S. Code, Federal Register, Code of Federal Regulations, Congressional Record, GAO reports, Supreme Court decisions and much more. The information provided on this site is the official, published version and the information retrieved from govinfo can be used without restriction, unless specifically noted.
A simple Google search which includes the search term "site:gov" will return only hits from state and federally published websites.
A service of the Catalog of U.S. Government Publications, MetaLib is a federated search engine that searches and retrieves reports, articles and citations, and also provides links to selected resources that are available online.
The official web portal of the U.S. Government