Although most of this large collection consists of papers of Lewis's legal practice, there are important groups which relate to the furnishing and maintenance of his city and country houses and the management of his farm, to the assembling of his outstanding collections of Asian and medieval illuminated manuscripts and of Babylonian clay tablets (now at the Free Library of Philadelphia), and to institutions with which he was closely associated, such as the American Philosophical Society, the University of Pennsylvania, and the Pennsylvania Academy of Fine Arts. Many letters and papers are about business (mortgages, rents, directorships in banks and insurance companies, and investments) and about the social and cultural life of Philadelphia (operas, libraries, museums, and schools for the handicapped).

The Thomas Jefferson papers contain a large number of correspondence both to and from Jefferson, as well as various other material related to American Revolutionary War and Early Republic. Includes correspondence with Patrick Henry, Charles Willson Peale, Richard Henry Lee, Horatio Gates, David Rittenhouse, Robert Patterson

From the Board of Trustees of the Estate of Stephen Girard, these films are the complete archive of one of the largest mercantile and financial operations in the United States of his day. The collection includes correpondence, with translations of letters in French (139 reels). It also includes bank records, account books, ledgers, cash books, and journals; papers, documents, and records of trading voyages (arranged by vessel and date); records of Girard's country house, "The Place"; records of real estate, rents, etc.; prices current of ports of the world. There is a card index of correspondents and ships (14 reels). Included is a card file, a unique and invaluable research tool, this is an index of names and places and alphabetical abstracts of Philadelphia newspaper items and advertisements for the period covering ca. 1718-1795. Roach made a systematic search through eighteenth-century newspapers and several other sources, for biographical and subject information on Philadelphians and Pennsylvanians of the period. It is primarily biographical , but subject headings, such as "The Barracks," "Blue Lion, Sign of the," "Custom House," are scattered throughout. The source of each entry is cited, and there are brief annotations. There is also a miscellaneous assortment of volumes that were received with the Kane family papers.