Papers of the American engineer, businessman, legislator (U.S. Senator from Vermont, 1946-1959). General correspondence (1923-1940); business correspondence (1930-1934); correspondence on screw threads and gear cutting standardization (1930-1938); correspondence relative to the Vermont Planning Board (1937-1939); senatorial correspondence (1946-1958); personal papers including articles, correspondence, photographs, scrapbooks, speeches, and a genealogy. Correspondents include George D. Aiken, Charles A. Beard, James F. Byrnes, Norman Cousins, Thomas E. Dewey, Dwight D. Eisenhower, Dorothy Canfield Fisher, Alvin H. Hansen, W. Averell Harriman, Herbert Hoover, Harry Hopkins, Harold Ickes, Lyndon B. Johnson, John F. Kennedy, Charles F. Kettering, Henry Cabot Lodge, Joseph McCarthy, Richard M. Nixon, Frances Perkins, Franklin D. Roosevelt, Edward R. Stettinius, Gerard Swope, Myron C. Taylor, Dorothy Thompson, Harry S. Truman, Henry Wallace, and Wendell Willkie.
Papers of the American legislator. McKinley was the Republican U.S. Representative(1905-1913; 1915-1920) and Senator (1920-1926) from Illinois. Collection includes correspondence, financial records, pamphlets, petitions, photographs, press releases, scrapbooks, and speeches, mostly relating to McKinley's roll as director of William H. Taft's renomination campaign prior to the Presidential election of 1912.