Correspondence, diary and notebook fragments, speeches, financial records, scrapbooks, printed matter, and other papers focusing chiefly on the political activities of Ruth Hanna McCormick Simms. Includes material concerning her congressional campaigns, activities on behalf of the Republican National Committee, work as presidential campaign manager for Thomas E. Dewey in 1944, and her reaction to economic depression and war. Marcus Alonzo Hanna's correspondence relates mainly to Ohio and national politics and also to his personal and business affairs. Includes copies of interviews (1905-1906) about him conducted by James B. Morrow with Joseph Benson Foraker, Theodore Roosevelt, and members of Hanna's family. Medill McCormick's papers relate to Illinois and national politics. Also includes papers relating to the Chicago Tribune and its publishers, Joseph Medill and Robert Rutherford McCormick, grandfather and brother of Medill McCormick. Family papers include correspondence between Ruth Hanna McCormick Simms and her daughter, Ruth McCormick Tankersley, known as Bazy.

Hanna's correspondents include his wife, Augusta Rhodes Hanna, and their daughter, Ruth Hanna McCormick Simms; and Benjamin Butterworth, J.C. Donaldson, Joseph Benson Foraker, Charles Foster, William McKinley, John Sherman, and John Wanamaker. Medill McCormick's family correspondents include his grandfather, Joseph Medill; mother, Katharine Medill McCormick; brother, Robert Rutherford McCormick; wife, Ruth Hanna McCormick Simms; and cousin, Joseph Medill Patterson. McCormick's other correspondents include Albert Jeremiah Beveridge, Edward Jackson Brundage, Calvin Coolidge, Joseph M. Dixon, Warren G. Harding, Charles Evans Hughes, Henry Cabot Lodge, Frank O. Lowden, William McKinley, Theodore Roosevelt, and George Richard Walker.