The Avalon Project; Documents in Law, History and Diplomacy
One of the best internet resources for primary documents, collected, annotated and kept up-to-date by Yale Law Department.
Internet Modern History Sourcebook
A huge collection of primary sources on a range of topics, part of the Internet History Sourcebook projects at http://www.fordham.edu/halsall/. Not very structured and not always up-to-date, but a lot of valuable sources.
Vietnam War bibliography by Edwin Moïse
The most successful effort to collect and categorize all publications on the Vietnam War. The site is constantly being updated.
Library of Congress
A portal to many more sub-sites with high quality resources on all aspects of American politics, culture and history.
American Folklife Centre
For resources on American cultural life (in a very broad sense).
National Archives of the United States
Digital National Security Archive
A site with declassified documents requested through the Freedom of Information Act. The subscribers area has well-prepared collections on a range of topics, but the free area also has valuable sources.
State Department FRUS-series
The Foreign Relations of the United States (FRUS) series contain the official historical record of US diplomacy. Recent publications available in pdf.
Congressional Record (1994-Present)
Constantly updated online archive of the Congressional Record.
Frontline Diplomacy: Foreign Affairs Oral History Collection
Transcripts of hundreds of interviews with US foreign service personnel serving all over the world. A treasure-trove of insights and information from those who worked at the front line of US diplomacy over the past decades.
Modern American Poetry
Lots of handy analyses of poems by modern American poets.
H-Amstdy Discussion Network
Keep informed and talk along with the American Studies community on H-Net.
The Internet Archive
Includes text, music, image, and moving picture databases.
Aboriginal Links Canada and the US
Truly exhaustive collection of links referring to documents by and about Canadian Aboriginals and Native Americans, including texts of original treaties and proclamations, legal acts from the 17th to the 21st century, information about individual tribes, centres, projects and university programs.
Farmworker Movement Documentation Project
Background information (including an excellent collection of original photographs, audio and video clips) on César Chavez’s Farmworker Movement and its function as precursor of the Chicano Civil Rights Movement.
Xroads Virginia Hypertext Project
Full online texts of many American authors.
Emily Dickinson Electronic Archives
Resources about the 19th-century poet and her manuscripts.