American Memory Project at the Library of Congress – "American Memory provides free and open access through the Internet to written and spoken words, sound recordings, still and moving images, prints, maps, and sheet music that document the American experience."
American President: A Reference Resource – "the most comprehensive resource on the history of the presidency and the nature of policy making available online; brought to you by the Miller Center of Public Affairs at the University of Virginia, the nation’s leading research institute for the study of the American presidency."
Avalon Project at Yale University – "digital documents relevant to the fields of Law, History, Economics, Politics, Diplomacy and Government"; covers from ancient times to the 21st century.
BBC History – British Broadcasting Corporation; historical periods; noted people in history; monarchs and heads of government; wars; archaeology; science.
Center for History and New Media - "bringing history to audiences worldwide by collecting digital records, archiving documents of the past, and presenting historical exhibits."
A Century of Lawmaking for a New Nation: U.S. Congressional Documents and Debates 1774-1873 – "consists of a linked set of published congressional records of the United States of America from the Continental Congress through the 43rd Congress, 1774-1875."
Chronicling America - Historic American Newspapers; "Internet-based, searchable database of U.S. newspapers; covers from 1836-1922."
Cold War International History Project - "collection of archival documents on the Cold War era from the once secret archives of former communist countries...internationally recognized as the world's preeminent resource on the Cold War."
Congress.gov – "official source for federal legislative information."
De Re Militari: The Society for Medieval Military History - "primary sources, articles, dissertations and resources for the study of military actions, technology, and topics from the fall of Rome to early seventeenth century."
Digital Book Index - "provides links to more than 164,000 full-text digital books."
Documenting the American South – "A digital publishing initiative that provides Internet access to texts, images, and audio files related to Southern history, literature, and culture from the colonial period through the first decades of the 20th century."
GPO – "The U.S. Government Printing Office disseminates official information from all three branches of the Federal Government."
Historical African American Newspapers Available Online - "list of historical African American Newspapers available online as part of digitization projects at libraries and historical societies as well as digitization projects done by Google."
Internet Medieval Sourcebook - medieval history sources.
Internet Modern History Sourcebook – "one of a series of history primary sourcebooks"; covers modern European history and American history, as well as modern Western Civilization and World Cultures."
John F. Kennedy - online presidential archive of primary-source documents from the Kennedy administration.
Making of America (MOA) - "digital library of primary sources in American social history from the antebellum period through reconstruction."
National Security Archive – "combines a unique range of functions: investigative journalism center, research institute on international affairs, library and archive of declassified U.S. documents."
New York Public Library Digital Collections - access to over 800,000 digitized items.
Perry-Castaneda Library Map Collection - An online map collection with historical maps and maps of U.S. cities.
Public Papers of the Presidents of the United States - "This online service makes available material that was compiled and published by the Office of the Federal Register, National Archives and Records Administration, in hardcover printed volumes entitled The Public Papers of the Presidents of the United States… January 1992 through December 2001."
United States National Archives & Records Administration - features online exhibits and documents.
United States Holocaust Memorial Museum: Resources for Academics and Research - personal stories, artifacts, encyclopedia and information on genocide.
University of Georgia Libraries, Hargrett Rare Book and Manuscript Collection: Historic Maps - Rare maps of the New World, Colonial America, Revolutionary America, Revolutionary Georgia, Union and Expansion, Civil War, Frontier to New South, Savannah and the Coast, and Transportation.
Weekly Compilation of Presidential Documents – "The Weekly Compilation of Presidential Documents is published every Monday and is the official publication of presidential statements, messages, remarks, and other materials released by the White House Press Secretary."
West Virginia & Regional History Center: Archives and Manuscripts - "largest historical/archives relating to West Virginia in existence."
The Gilder Lehrman Center for the Study of Slavery, Resistance, and Abolition - "dedicated to the investigation and dissemination of knowledge concerning all aspects of chattel slavery and its destruction."
Historical Census Browser - "examine state and county topics for individual census years...examine multiple topics within a census year...produce tables of data by state or county...sort data by selected categories...creat ratios between any two data categories..." From 1790 to 1960.
Veterans History Project - "collect and preserve stories of wartime service...World War I, World War II, Korean War, Vietnam War, Persian Gulf War, Afghanistan and Iraq conflicts..."
Voices of Civil Rights - "personal accounts of America's struggle to fulfill the promise of equality for all."
EuroDocs: Primary Historical Documents from Western Europe- "links connect to Western European (mainly primary) historical documents that are transcribed, reproduced in facsimilie, or translated."
The World War I Document Archive - "archive of primary documents from World War I."
World War I Remembered - BBC News site documents from WWI such as archive radio interviews, images and newsreels, and letters from soldiers.
Historic Government Documents from World War II - "contains 343 informational pamphlets, government reports, instructions, regulations, declarations, speeches, and propaganda materials distributed by the U.S. Government Printing Office during the Second World War."
POTUS (Presidents of the United States) - information on all United States Presidents compiled by the Internet Public Library.
Society for Historians of American Foreign Relations - "dedicated to the scholarly study of the history of American foreign relations."