You can search for articles using databases or indexes. Many provide the full text of the article, while some databases display a link to library holdings, i.e., does the Auraria Library provide access to this article?
The Colorado Historic Newspapers Collection (CHNC) currently includes digitized pages representing individual newspaper titles published in Colorado from 1859 to 1923. Due to copyright restrictions, CHNC does not generally include newspapers published after 1923.
There are a number of local cultural institutions that could be very valuable to your research. Examples include:
Contact colleagues and professors in your department, and across the globe. Listservs may be a great tool to communicate or get ideas for your research.
Your local librarian may also be a great source of information!