There are two primary national sources for information on Olmsted and the Olmsted firm: the Olmsted Archives at Frederick Law Olmsted National Historic Site, National Park Service, and the Olmsted Papers and Records at the Manuscript Division of the Library of Congress.
The Manuscript Division of the Library of Congress contains most of the firm’s written correspondence and administrative files, which support and explain the drawing files held at the Olmsted National Historic Site.
The Manuscript Division includes two important collections related to the work of the Olmsted firm: the Frederick Law Olmsted Papers and the Olmsted Associates Papers. Detailed finding aids for both collections are available online. The Manuscript Division also houses the papers of Laura Wood Roper, Frederick Law Olmsted’s first biographer.
Guide to the Olmsted Papers and Records at the Library of Congress 
Other Major Repositories with Significant Olmsted Collections
The Frances Loeb Library at Harvard Design School John Charles Olmsted Collection includes some 5,000 letters Olmsted exchanged with his wife, Sophia White Olmsted (1862-1956), during the years 1898-1920. During this period Olmsted traveled for lengthy periods on firm business and this correspondence provides insight into the realities of both practice and domestic concerns. There are also correspondence files with professional colleagues, scattered manuscript materials of professional interest, as well as family papers, ephemera and photographs.
The Archives of American Gardens, part of the Smithsonian Gardens, includes a collection of approximately 60,000 photographic images and records that document historic and contemporary gardens throughout the United States.
The Catalog of Landscape Records in the United States, formerly at Wave Hill and now located at the New York Botanical Garden, lists landscape records including plans, drawings and photographs that are contained in other repositories across the country. Information is still being collected and the Catalog focuses on landscape records generally, not just the work of the Olmsted firm.
