- Columbia Institution for Instruction of Deaf and Dumb (Interior Department)1
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- Columbia, Department of the2
- Columbus Memorial Commission1
- Combined Production and Resources Board, United States, Great Britain, and Canada4
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- Command and General Staff College (Army)1
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- Command and General Staff College, Fort Leavenworth (Army)31
- Command and General Staff School15
- Command and General Staff School, Fort Leavenworth11
- Commerce Committee2,695
- Commerce Committee, Senate2,821
- Commerce Court57
- Commerce Department4,307
- Commerce Department Aeronautics Branch6
- Commerce Department Census Bureau48
- Commerce and Labor Department464