The papers of William Mahone span the period 1853 to 1895, with the bulk of the material dating from 1876 to 1892. The collection consists of copies of letters written by Mahone to others, incoming letters to Mahone, subject files on a variety of topics, clippings, and scrapbooks, but primarily focuses on Mahone's railroad and political interests. There is a great deal of overlap of topics between the different series in the collection; thus information concerning Mahone's political and railroad interests is repeated in the different series.