Primary sourcesare original records created at the time historical events occurred or could also be memoirs and oral histories of past events. 

• In  your search: include the words - diary, diaries, letters, papers, documents, documentary or correspondence.

• Combine these these terms with the event or person you are researching. (example: civil war diary)

• Also search by subject for specific people and events, then scan the titles for those keywords or others such as memoirs, autobiography, report, or personal narratives.

The internet has helped to make many of these sources widely available, some of the best sources are:

American Memory Project of the Library of Congress
http://memory.loc.gov/ammem/index.html

The Avalon Project of Yale University
http://avalon.law.yale.edu/default.asp

Digital History of the University of Houston
http://www.digitalhistory.uh.edu/other_documents/other_documents.cfm

Digital Public Library
http://dp.la/ 

EuroDocs
http://eudocs.lib.byu.edu/index.php/Main_Page

Hathi Trust
http://www.hathitrust.org/

Internet Archive
http://archive.org/ 

Making of America
http://quod.lib.umich.edu/m/moagrp/

World Wide Web Virtual Library
http://vlib.iue.it/history/index.html

Don't forget about our subscription to the Historical New York Times: from 1851-present,  password available in Library or on Portal, click here for Jing tutorial

For more information on using and evaluating primary sources on the web, visit the ALA:
http://www.ala.org/ala/mgrps/divs/rusa/sections/history/resources/pubs/usingprimarysources/index.cfm