The Library of Congress' Chronicling America project
This site offers free access to digitized newspapers published between 1690 and 1963 from various states.You can search and view full-text issues from this time period.
Free Historic U.S. Newspapers by State
This guide provides access to digitized free historic newspaper resources by U.S. state and are arranged alphabetically by state. Holdings vary by date and location. Some are provided by the Library of Congress' Chronicling America website and others may be provided by state historical societies, public or university libraries, and state libraries and archives
The California Digital Newspaper Collection
UC Riverside provides free access to digitized California newspapers published since 1846, including titles like The California Star, Daily Alta California, and San Francisco.