The Library has an extensive collection of historical newspapers in a variety of formats, including original print, microfilm, and digital reproductions. Not all of them are included in the online catalog, but if you are looking for a particular newspaper title, you should use the UIUC Newspaper Database (see below for link).
Many newspapers are embedded in larger collections of online resources, such as Ethnic News Watch (1960-present ). They may also be embedded in microfilm collections, such as the Underground Press Collection (1963-1985).
To find a specific newspaper, or to identify newspapers published in a specific year or place, or newspapers published for a specific audience (e.g. African Americans, or socialists), or to identify newspapers that are part of larger collections like the Underground Press Collection, use the University of Illinois Library Newspaper Database:
A catalog of newspapers at the University of Illinois Library. Lists newspapers in all formats--print, microfilm, and digitized. You can search for newspapers by title, or identify newspapers by place of publication, date of publication, or by the newspaper's subject or intended audience. Only includes newspapers that are either the original print publication, or else facsimile reproductions of the original print publication.