Washington and Lee University
Encyclopedia of American Foreign Policy. (2nd ed.) Scribner's.
Available online as of 10/26/06.
Also in printed form in the Reference collection: REF E 183.7.E52 2002 (3 volumes)
About 120 essays.
Dictionary of American History. (3rd ed.) Scribner.
Available online.
Almost certainly the most useful encyclopedia for overviews of topics in American history. Sample entries:
"Arms Race and Disarmament" and "Panama Canal."
Country Profiles.
Available online.
Leyburn Library
compilation of resources useful for summarizing political and economic conditions, forms of
government, statistics, etc. for countries of the world.
Historic Documents.
Available online.
Texts and commentary on over 3,000 documents (1972-date), ranging from "presidential speeches, international agreements, and
Supreme Court decisions to U.S. governmental reports, scientific findings, and cultural discussions."
There is a chronological arrangement ("Browse by Title") and a "Search the Series" option. Example
of a search: "panama canal"
American Presidency Project.
Available online.
Probably most useful for its (unique?) database of presidential papers, speeches, etc.
Choose Documents (near top of page)
for various browsing options and the ability to "Search the Entire Document Archive."
National Security Archive.
Available online.
The official collection of publicly-available (some de-classified) U.S. diplomatic documents is the State Department's Foreign Relations of the United States, but that series has a 30-year publication time-lag.
George Washington University's National Security Archive can provide some diplomatic documents created during that span, along
with commentary.
Catalog of U.S. Government Publications.
Available online.
Online database contains over 500,000 citations to electronic and print publications from the U.S. Government. Coverage extends back to 1976, with updates daily,
with plans to eventually include publications dating back to the late 1800's.