The History, Philosophy, and Newspaper Library at UIUC has compiled an enormous list of newspapers available online, both subscription-based and free. They include major newspaper titles with dates of publication as well as local and international digital newspaper collections with descriptions and access information.
The Illinois Digital Newspaper Collections is a project of the History, Philosophy, and Newspaper Library at the University of Illinois. The works collected include digital facsimilies of newspapers and trade journals in a variety of fields. Access to 69,528 newspaper issues comprising 919,570 pages and 6,648,636 articles!
Google News Archive provides free access to scanned archives of newspapers and links to other newspaper archives on the web, both free and paid. Not complete, but you might get lucky.