Copyright is a confusing issue. This string and another on the board about photographs indicate we need to know more. The reproduction of a newspaper article for informational (scholarly) use falls under the fair use provisions of copyright law. For example images from newspapers included in an IOTD on the Chipboard could be considered a use for study and research. Problems may arise when articles are used in a commercial publication like a book so I would ask for permission.

Online newspaper databases like Newspaperarchive.com and Genealogybank.com, as A. J. pointed out, pay fees to newspapers and sell access to researchers. Licensing agreements subscribers agree to preclude copyright, but these two databases recognize fair use for scholarly research. They do prohibit downloading substantial amount of content and reselling it. I think, too, that copyright remains usually with the newspaper rather than the online provider.

Copyrights do expire. Generally anything published before 1923 is in the public domain but if published later copyrights may still be in effect.