Contains first-hand accounts and retrospective articles on the South American Expedition. Includes diaries, correspondence, field notes, and articles. Much of the material focuses on the contributions of Benjamin Cluff Jr. and Chester G. Van Buren. Collection was compiled by Vasco M. Tanner, and includes his own research and writing on the expedition.

Contains handwritten journals, typescripts of journals, handwritten and typewritten correspondence to, from and concerning Van Buren and the expedition, supply lists, financial papers, certificates, passports, maps and photographs concerning the expedition. The majority of the material dates from 1900-1903.