American Memory: Historical Collections for the National Digital Library   "Provides access to more than seven million digital reproductions of primary sources from more than one hundred important historical collections from the Library of Congress and other participating museums and institutions."

ArchiveGrid Search index records for millions of historical manuscripts, letters, personal papers and more held in thousands of important museums, libraries and institutions. These documents have not been digitized for retrieval. Still a very good source for locating primary source material in the field of history.

History Resource Center: U.S. Published by Gale/Cengage Learning. An online full-text database comprising encyclopedias and reference books, journals and periodicals, and primary sources relating to U.S. history.

History Resource Center: World Published by Gale/Cengage Learning. An online full-text database comprising encyclopedias and reference books, journals and periodicals, and primary sources relating to World History.

The Making of America Project  Cornell server.  University of Michigan server.  A joint project of Cornell University and the University of Michigan, this project presents a digital library of primary sources in American social history from the antebellum period through reconstruction.

Perseus Digital Library   A digital library of primary and secondary sources for the study of Classics, Humanities and History.