These records are amongst the most frequently used collections, and the most historically important records, in the Archives. US National Museum (USNM) incumbents included:
- Spencer F. Baird, 1850–1881
- G. Brown Goode, 1881–1896, including the years 1881–1887 when he served as Assistant Director of the Museum without the title of Assistant Secretary
- Charles D. Walcott, Acting Assistant Secretary, 1897–1898
- Richard Rathbun, 1897–1918
- William de Chastignier Ravenel, 1918–1925, with the title Administrative Assistant to the Secretary, in charge of the USNM
- Alexander Wetmore, 1925–1948
- Remington Kellogg, Director, USNM, 1948–1962
- Frank A. Taylor, Director, USNM, 1962–1967
Important Record Units include:
- Record Unit 52, Incoming correspondence of Spencer F. Baird as Assistant Secretary, 1850–1877
Spencer F. Baird's correspondence survived the 1865 Smithsonian Castle fire, making it amongst the oldest Smithsonian records in the Archives. This collection contains a wealth of information on the early history of the Smithsonian and the development of the USNM. There is much correspondence with collectors and participants in expeditions in the field. The records are indexed by a card file, as well as individually, in each volume. Letters dated 1875–1877 are indexed as part of the Secretary's records (Record Unit 26), vols. 184-209. Contact the Archives Reference Team for further information about this collection.
- Record Unit 53, Outgoing correspondence of Spencer F. Baird, 1850–1877 This correspondence is in response to incoming letters in Record Unit 52. It is indexed by card file and tissue copies exist in letterpress volumes. The Record Unit is on microfilm.
- Record Unit 189, Incoming correspondence of G. Brown Goode, 1881–1996; C. D. Walcott, 1897–1898; and Richard Rathbun, 1898–1908
This rich collection documents expeditions and collecting work; acquisition of collections; and the administration and operation of museum divisions and departments.
- Record Unit 112, Outgoing correspondence, 1879–1907
Responses to incoming letters are in Record Unit 189 (and a few years of Record Unit 192). Tissue copies in letterpress volumes exist for this collection. The Record Unit is on microfilm. This correspondence is indexed (along with Record Unit's 113, 114, 115, and 109) in Record Unit 116 and is also on microfilm.
- Record Unit 192, USNM, Permanent Administrative Files, 1877–1975 (with most material dating from 1902)
This Record Unit contains incoming and outgoing correspondence of Richard Rathbun, William deC. Ravenel, Alexander Wetmore, and A. Remington Kellogg. These records comprise the central USNM file covering roughly sixty years. Included are files documenting collecting trips and expeditions, USNM involvement at international expositions, permanent and temporary museum exhibits, the acquisition of collections, and miscellaneous subjects such as the museum's activities during World War II. In addition, it is the primary USNM public inquiry file. It is arranged by sequential register numbers and indexed by a card file on microfilm. The original index (which also indexes Record Unit 305) is in the Registrar's Office, National Museum of Natural History.
- Record Units 54, 55, 88, 89, Files of Assistant Secretaries Goode, 1877–1896 (54); Rathbun, 1897–1918 (55); and Kellogg, 1925–1968 (88 & 89)
These small record units consist mostly of various administrative records. Goode's files include materials concerning the United States Fish Commission.
- Record Unit 158, Curators' Annual Reports, 1881–1964
This collection includes annual reports prepared by USNM curators, preparators, administrators, and others, and submitted to the Assistant Secretary. These reports often contain more information than what ended up in the published Annual Reports of the USNM. Record Unit 408 consists of manuscript annual reports of USNM preparators and taxidermists.
- Record Unit 201, G. Brown Goode's internal correspondence (incoming), 1875–1902
This collection consists of Goode’s internal correspondence with his staff (curators, honorary curators, preparators, and administrative staff). Materials also include Goode's correspondence with US Government agencies. Outgoing replies, 1879–1907, will be found in Record Units 112 and 113.
- Record Unit 305, Accession Records of the US National Museum, circa 1850–1958. This Record Unit is available on microfilm arranged numerically, and indexed (with Record Unit 192) via a microfilmed card index by donor name. Not only are these records the primary documentation of the national collections, but also a rich source of information on collecting expeditions, Western US exploration, and Smithsonian history, among other topics. Contact the Archives Reference Team for further information about this collection.