The collection includes the correspondence and other papers of William Channing Gannett (1840-1923), who was a Unitarian minister in St. Paul, Minnesota (1877-1883) and Rochester, N.Y. (1889-1908). The correspondence to and from Mr. Gannett includes letters from Jane Addams, Abigail May Alcott, Susan B. Anthony, Samuel Longfellow, Elihu Root, Alphonso and William Howard Taft, Booker T. Washington, Frank Lloyd Wright and many Unitarian leaders of the late 1800s and early 1900s. There are also letters relating to the Western Unitarian Controversy, the education of the freedmen at Port Royal, the temperance crusade, Unity magazine, Unitarian church organization and membership, and to the editing of Unity Hymns and Chorals by Mr. Gannett and Frederick L. Hosmer. About 400 letters, dated 1875-1912, were added to the collection by Charles H. Lyttle and relate to the Western Unitarian Controversy.