Archival Research Catalog - Online catalog of the U.S. National Archives and Records Administration. The Archival Research Catalog (ARC) is the online catalog of NARA's nationwide holdings in the Washington, DC area, Regional Archives and Presidential Libraries.
Foreign Relations of the United States - Official historical records of major U.S. foreign policy decisions, from the Departments of State and Defense, the CIA, other foreign agencies, and private individual papers. This is a project of the University of Wisconsin-Madison Libraries in collaboration with the University of Illinois at Chicago Libraries. It is an incomplete run from 1861-1960 with missing volumes being added as they can be acquired and processed.
GPO Access - The U.S. Government Printing Office provides official information from all three branches of the Federal Government, including the public papers of the U.S. presidents from 1991 forward.