The Sullivaniana collection is largely the gift of George Elmslie, one of Sullivan's last colleagues and the executor of his estate. This grouping forms the largest extant collection of Sullivan documents (excluding architectural and design drawings). Among Sullivan's contributions to the development of modern American architecture was the new aesthetic for the visual organization of tall buildings: a strong base at grade level, top floors capped with an eye-arresting cornice, and the general office floors in the central shaft repeatable ad infinitum. Sullivan was one of the most prolific architect/critics of the late 19th and early 20th centuries and numerous draft manuscripts and typescripts of his writings are held in this collection. Also included are sketches, personal and business correspondence, personal and project photographs, and memorabilia.
In 1910 John D. Van Allen commissioned Louis Sullivan to design a new department store for his family business in Clinton, Iowa. By this date Sullivan had few commissions and thus spent considerable time attending to his immediate projects. In frequent letters to his client (occasionally daily), Sullivan wrote of his design, guiding and persuading the client toward Sullivan's desired end. In addition to more than one hundred letters, the collection includes financial documents and rare construction photographs.