Here are a few links to related sites:

U.S. Government Site
Library of Congress
America's Library
American Memory (Library of Congress/National Digital Library)
National Archives and Records Administration
American History 102: Civil War - Present (University of Wisconsin - Madison)
Hitchhikers Guide to American History
Douglass Archives
History Channel
A Biography of America (PBS Series)
The History Net
Historic Traveler
MultiEducator (scroll down to online resources)
Hypertext on American History
Making of America - digital library of primary sources
U.S. Congressional Documents and Debates
University of Oklahoma Law Center (historical documents)
U.S. Constitution Online
National Constitution Center
Supreme Court Decisions Since 1893
Cultural Maps - University of Virginia
Tales of the Early Republic
C-Span series (presidents)
Time Covers
Historic Sound Clips
Matrix Resources (list of audio archives)
Radio Days
TeacherNet - Colonial America (MANY resources)
National Musuem of American History (Smithsonian)
Internet Public Library
StudyWorld/Homework Helper
Women and Social Movements in the United States 1830-1930 - Binghamton University
Historical Text Archive (private site with pop-up and many cookies)
Presidential Libraries
Colonial Hall (Founding Fathers)
Founder's Constitution
Infoplease - Year-by-Year
Infoplease - United States

Library of Congress Map Collections

American History Through Film