- Civilian Production Administration38
- Claims Committee5,460
- Claims Committee, House7,738
- Claims Committee, Senate6,240
- Claims, Committee on333
- Classification Division33
- Clearinghouse for Federal Scientific and Technical Information59
- Coal Commission7
- Coal Research Office119
- Coast Artillery Division3
- Coast Artillery Fire Board8
- Coast Artillery Office32
- Coast Artillery Office (formerly Artillery Office)1
- Coast Artillery School23
- Coast Artillery School, Fort Monroe8
- Coast Guard2,673
- Coast Guard Academy2
- Coast Guard Academy, New London6
- Coast Guard and Transportation, Bureau of1
- Coast and Geodetic Survey13,767