There are two categories of correspondence in the Charles D. Rosa Papers. The first is political correspondence which is almost entirely taken up with Rosa's term in the 1917-1918 legislature and his unsuccessful senatorial campaign of 1926; and the second is general correspondence, the bulk of which is made up of his official correspondence as Tax Commissioner. Important correspondents in the Political Correspondence are John J. Blaine, Stephen Bolles, Henry Allen Cooper, Herman Ekern, William Evjue, James A. Frear, Walter S. Goodland, Merlin Hull, Paul Husting, Ada James, Richard Lloyd Jones, Robert M. La Follette, Solomon Levitan, and Charles R. Van Hise. In the General Correspondence are exchanges with Glenn Frank, James A. Frear, Merlin Hull, Philip La Follette, Robert M. La Follette, Jr., and Fred Zimmerman.
Articles and addresses cover the wide range of Rosa's interests. The book manuscripts are all from after his retirement from the Tax Commission, and most of the notebooks appear to be research materials he was gathering to help him in writing other books.
Of the remaining personal papers, Rosa's reference notes on taxation deserve special mention. These notes consist of typewritten, indexed summaries of practically all Wisconsin court cases involving taxation, 1900-1938.
The miscellaneous Tax Commission materials were retained in the collection in order to illustrate the scope of Rosa's duties for that office.
