Kelvin Smith Library
KSL hosts several collections of major American newspapers in full text, spanning the 19th and 20th centuries. See the link below for a full list. You can also use the Lexis Nexis Academic database for news coverage back to 1980.
The Readers' Guide is a key research resource for exploring 20th century American history and popular culture as chronicled in mainstream periodicals. KSL has a print copy of this multi-volume index on the first floor of the library.