Avalon Project
(full, sourced documents in American History 1492 - Present, from Yale Law School)
Chronicling America: Historic American Newspapers
(National Endowment for the Humanities in cooperation with the Library of Congress, provides access to United States newspapers, full access from 1880-1922)
History Matters
(U.S. survey course on the web, from The American Social History Project/Center for Media and Learning of the
City University of New York and the Center for History and New Media at George
Mason University)