- Capitol Building and Grounds Superintendent (formerly Architect of Capitol)2
- Capitol Building and Grounds, Superintendent of the3
- Capitol Building, Joint Commission on Plans for Extension and Completion of2
- Capitol Grounds, Commission for Enlargement of2
- Capitol Grounds, Commission for Enlarging of2
- Capitol Grounds, Commission on Enlarging1
- Capitol, Strength and Safety of Roofs over Senate and House Wings of, Special Joint Committee to Investigate2
- Capitol, United States Commission for Extension of1
- Card Division61
- Card Section21
- Card Section (Library of Congress)12
- Carlisle Indian School76
- Catalog Division109
- Catalog Division, Library of Congress2
- Catalog Maintenance Division6
- Catalogue Division83
- Catalogue Division, Library of Congress5
- Cavalry School2
- Cavalry and Field Artillery School16
- Cavalry and Field Artillery, School of Application for (War Department)1