The library subscribes to many newspaper databases. Check this page for a complete list. Here are three that will get you started.
This database offers full-text and full-image articles from the New York Times and Washington Post; the collection includes digital reproductions of every page from every issue in downloadable PDF files.
Newspapers published in the 19th and 20th centuries. Created in partnership with the Wisconsin Historical Society, the Kansas State Historical Society and the Library of Congress.