Citations for archival materials are often institution-specific. Please consult holding institutions, finding aids, or other guides for preferred citations.
Generally, for footnotes or end notes you cite archival materials in collections by the item, box number, folder number, collection name and number, and institution.
Sometimes archival collections do not have box numbers or folder numbers.
Here are some examples:
Petition, The City of El Paso to the Texas Centennial Commission, MS419, C.L. Sonnichsen Special Collections Department, The University of Texas at El Paso Library.
“El Pasoans and the Neighbors Greet You Amigo!,” program, Box 28, Folder 16, Cleofas Calleros papers, MS231, C.L. Sonnichsen Special Collections Department, The University of Texas at El Paso Library.
See The Chicago Manual of Style for more information.