Correspondence, diaries, speeches and writings, financial papers, family papers, clippings, scrapbooks, and printed matter documenting Johnston's career as a photographer of national figures and events (1889-1910), her photography of gardens and estates (1913-1926), and her compilation of a photographic record of Southern colonial architecture (1927-1952). Includes material relating to her involvement in the Pictorialist movement; work for Ladies' Home Journal, McClure's, and Town & Country magazines; participation in international exhibitions in Chicago (1893), Paris (1900), Buffalo (1901), and St. Louis (1904); travels in Europe; her studios in Washington, D.C., and New York, N.Y., the latter in partnership with Mattie Edwards Hewitt; and the emerging role of women in the profession of photography.

Family members represented include Johnston's aunt, Cornelia Benjamin Hagan, and her mother, Frances Antoinette Benjamin Johnston. Correspondents include Henry Adams, Nellie Allen, George Grantham Bain, Charles I. Berg, Edward William Bok, William Lawrence Bottomley, Zelda Branch, H.I. Brock, Elizabeth Cameron, Edmund S. Campbell, Bliss Carman, Jo Hubbard Chamberlin, Frances Folsom Cleveland, George B. Cortelyou, Paul Philippe Cret, Theodore Dreiser, George Eastman, Hollis Burke Frissell, Walter Gay, Phoebe Apperson Hearst, A. Horsley Hinton, Leicester Bodine Holland, Joseph C. Hornblower, B.F. Johnson, Gertrude Käsebier, Frederick P. Keppel, Hans Kindler, Clara E. Laughlin, Waldo Gifford Leland, Antoine Lumière, James Rush Marshall, Charles Follen McKim, John C. Merriam, Margaret Mitchell, Charles Moore, Frederick Law Olmsted, Augusta Owen Patterson, Edward Penfield, Ethel Reed, Eva Watson Schütze, Alfred Stieglitz, Ida M. Tarbell, Mills Thompson, John Wanamaker, Catharine Weed Barnes Ward, H. Snowden Ward, Thomas Tileston Waterman, H.J. Whigham, Waddy B. Wood, and Walter E. Woodbury.