The American Historical Association (AHA) was founded in 1884 and encompasses every historical period and geographical area and serves professional historians in all areas of employment.
An outstanding and invaluable site for American history and general studies. Contains primary and secondary documents, exhibits, map collections, prints and photographs, sound recordings and motion pictures.
This impressive site from Steven Mintz at the University of Houston includes an up-to-date U.S. history textbook; annotated primary sources on United States, Mexican American, and Native American history, and slavery; and succinct essays on the history of ethnicity and immigration, film, private life, and science and technology.
The NARA offers federal archives, exhibits, classroom resources, census records, Hot Topics, and more. In addition to its paper holdings (which would circle the Earth 57 times) it has more than 3.5 billion electronic records.
