This collection consists of personal, professional, and official papers of Walcott and his family; some of the papers postdate Walcott's life. Included are diaries, 1870-1927, which document many of Walcott's official, personal, and family activities; personal correspondence which documents Walcott's participation on several governmental committees such as the National Advisory Committee for Aeronautics, and the Committee on Organization of Government Scientific Work, as well as several private conservation groups, and his appointment as Director of the United States Geological Survey; family correspondence with relatives and his immediate family concerning their investments, the deaths of one of his sons and one of his wives; correspondence concerning the role of his son, B. Stuart Walcott, in World War I and plans for memorials for him and his flying corps; family legal documents and financial records; scrapbooks and newspaper clippings documenting the activities of Walcott and his family, especially concerning his appointment as Secretary of the Smithsonian; biographical materials prepared by Walcott as well as others, including correspondence and an unpublished biography of Walcott by Adele Jenny; degrees and honors; popular, scientific, and official speeches; correspondence documenting part of Walcott's tenure with the United States Geological Survey as well as reports of his USGS research and participation on several conservation committees and a government organization study committee; drafts of manuscripts, drawings of geologic formations, and field notes, including some by Charles Elmer Resser, Ray S. Bassler, and Edward Oscar Ulrich, documenting Walcott's research in geology; photographs of Walcott, his family, and geologic formations, with special emphasis on the Rocky Mountains; records, including correspondence, minutes of various boards and committees, and reports documenting Walcott's active role in the Carnegie Institution of Washington, the National Academy of Sciences, the National Research Council, the Washington Academy of Sciences, and the George Washington Memorial Association; and publications of Walcott and related ones by other scientists.