• U.S. History: US History.org
  Developed by The Independence Hall Association in Philadelphia

• Presidential Elections 
  History Channel. Videos, pictures, speeches.

• HippoCampus.org
  U.S. History Since 1877. Recommended website.

• Khan Academy: U.S. History
  Learning sequences, very well structured. 

• Digital History at the University of Houston
  Great interactive website. 

• A Biography of America
  Annenberg Learner. Well-elaborated resources. 

• Internet History Sourcebooks Project 
  Selected Sources Sections on Modern History

• The Gilder Lehrman Institute of American History - History by Era 
  Essays, Primary Sources and Multimedia for each Era and Sub-Era, written by distinguished scholars

• The Gilder Lehrman Collection 
  Unique archive of primary sources in American history