You can search on the Internet for primary sources by adding the phrase "primary sources" in your search or any of the following terms:
For a famous primary source – i.e., the Declaration of Independence – in the search box, include quotation marks around the title and include the word text or transcript
100 Milestone Documents
Includes documents that chronicle United States history from 1776 to 1965.
America from the Great Depression to World War II
The photographs in the Farm Security Administration - Office of War Information Photograph Collection form an extensive pictorial record of American life between 1935 and 1944. This U.S. government photography project was headed for most of its existence by Roy E. Stryker, who guided the effort in a succession of government agencies: the Resettlement Administration (1935-1937), the Farm Security Administration (1937-1942), and the Office of War Information (1942-1944).
American Historical Documents
Text of 47 treaties, speeches, historical accounts and governmental documents that trace U.S. history from the settling of the continent to the founding of the country to the Civil War and early twentieth-century international relations.
American Journeys
Eyewitness accounts of North American exploration, from the sagas of Vikings in Canada in AD1000 to the diaries of mountain men in the Rockies 800 years later.
American Memory
"American Memory provides free and open access through the Internet to written and spoken words, sound recordings, still and moving images, prints, maps, and sheet music that document the American experience. It is a digital record of American history and creativity."
C-SPAN Video Library
The video library records, indexes, and archives all C-SPAN programming for historical, educational, research, and archival uses. Every C-SPAN program aired since 1987, now totaling over 170,000 hours, is contained in the C-SPAN Archives.
Library of Congress Digital Collections
The LOC presents special collections covering American History and Culture, Historic Newspapers, Sound Recordings, Prints and Photographs, and so much more including the Primary Source Sets.
National Archives and Records Administration (NARA)
NARA preserves historically valuable archives of the U.S. government, including documents, photographs, images, maps, audio clips, letters, speeches, and films.
Covers U.S. government information resources, including Congressional, judiciary, and executive branch documents.
These lists were published in the College and Research Libraries News :
Birkenseer, S. (2015). The American Civil War: A collection of free online primary sources. College & Research Libraries News, 76(5), 269-273. doi:https://doi.org/10.5860/crln.76.5.9314
Kershner, S., & Mannheim, M. (2015). A guide to Vietnam War resources: Government documents, oral histories, antiwar movements. College & Research Libraries News, 76(9), 511-514. doi:https://doi.org/10.5860/crln.76.9.938
Collection of oral histories relating to the May 4, 1970 shootings at Kent State University in Kent, Ohio. Includes eyewitness accounts of the event and its aftermath from students, faculty, residents and guardsman.