The Correspondence series includes letters introducing Ludlow as Washington representative of the Indianapolis Sentinel, 1901; letters congratulating him on his transfer to Washington correspondent of the George F. McCulloch's chain of papers, the Indianapolis Star, the Muncie Star, and the Terre Haute Star, 1903; a tribute to Colonel Charles A. Lindbergh, 1927; letters and articles on Indian mounds in Indiana and Ohio, 1928; and letters from the 1930s on Townsend's old age pension plan.

Correspondence also includes letters and petitions on the Peace Amendment which proposed to amend the Constitution of the United States to provide for a referendum vote on war and to take the profit out of war, 1935-1940. Presidents of universities and colleges, ministers, religious organizations, railroad brotherhoods, other labor organizations, American Association of University Women, the League of Women Voters, American War Mothers, National Grange, Women's Christian Temperance Union, business and professional women's clubs, peace organizations, prominent men and women in all professions, and the common people all supported the amendment. In spite of numerous letters from congressmen and senators to vote for the bill, it was defeated. Letters of regret from the rank and file followed the announcement of the vote.

Included are also letters congratulating Ludlow on receiving an honorary LLD from Butler University in 1940; letters regretting his decision not to stand for re-election to Congress in 1948; and copies of two letters September 14 and November 10, 1839, from Charles Mayer, founder of Charles Mayer & Co. of Indianapolis, to friends in Germany giving an account of his voyage from Germany to Baltimore, his trip from Baltimore to Cincinnati, and his first jobs in Cincinnati and Indianapolis.

Printed materials include unbound clippings and two printed publications.

The Scrapbooks series contains newspaper clippings of articles and speeches by Ludlow, articles about him, and articles of interest to him; pictures; pamphlets; leaflets; and press releases. They are organized into subseries as follows: numbered scrapbooks, 31 volumes and two volumes of index, 1863-1948; scrapbooks of material relating to Ludlow's efforts for a constitutional amendment giving the electorate the right to vote on U.S. participation in foreign wars, eight numbered volumes and one index volume, 1923-1948; four unnumbered scrapbooks of clippings, Nov. 1901-Mar. 1903, Jan.-July, 1913 and 1927-1928. The first three unnumbered scrapbooks contain clippings of newspaper articles by Ludlow. In addition to the indexes for the first two series of scrapbooks, there are three scrapbook indexes on cards as follows: a subject index, a title index, and an index by names of newspapers.

Writings includes bound typescripts of two of Ludlow's publications, In the Heart of Hoosierland: A Story of the Pioneers, Based on Many Actual Experiences (1925) and Hell or Heaven (1937).

Note on Indexing Term - "Law": Among the papers are letters and petitions on the Peace Amendment which proposed to amend the Constitution of the United States to provide for a referendum vote on war and to take the profit out of war, 1935-1940.