The San Diego Union-Tribune and its predecessors are available in a mix of formats.
Online access (restricted to UCSD users) is available for:
Microfilm access is available for issues from 1871-present. The newspaper has gone through various name changes, but all are together at call number XF 248. Microfilm provides cover-to-cover page images of all issues.
Documents attached to news stories -- archive (2005, 2008-16) of supplemental documentation attached to UT San Diego articles.