A more extensive list of online newspaper resources are available from the Library's Electronic Resources Finder. Some of these are only aggregated collections of links to U.S. and international newspapers, not all of them contain searchable, full-text articles.
Historical Newspapers (ProQuest)
Indexes articles from Chicago Defender (1905-1975), Chicago Tribune (1849-1986), Los Angeles Times (1881-1986), New York Times (1851-2004), San Francisco Chronicle (1865-1922), Wall Street Journal (1889-1990), and Washington Post (1877-1991).
This site allows users to search and view newspaper pages from 1880-1922 and find information about American newspapers published between 1690-present. To date, over 200,000 pages of California newspapers have been digitized.