Contains an expedition journal documenting Van Buren's activities between August and October 1903. Also includes a wallet with train tickets, business cards, signatures, and personal notes.

Contains typescripts of journal entries translated from Spanish to English. Entries are taken from the July 10, 1902-June 28, 1903 and August 4-October 16, 1903 journals. References to pages in original journals are included.

Contains letters between Van Buren and his parents, Joseph B. Keeler, Benjamin Cluff Jr., and B. Thomas Higgs Jr. Contents focus on the activities and finances of the South American Expedition. Materials date from between 1900 and 1903.

Contains correspondence between Van Buren, Edwin S. Hinckley, and Edward H. Holt. Also includes correspondence by his wife, Verena Van Buren, with Vasco M. Tanner and Franklin S. Harris, and a citizenship statement. Materials date from between 1904 and 1906, with items from 1929 and 1933.

Contains handwritten and typewritten receipts, and a handwritten list of donations for the expedition. Materials date from between 1900 and 1904.

Contains a typewritten supply list for the South American Expedition. Materials date from 1900.