- C.B. Knox Gelatine Co (Johnstown, N.Y, 1924) (1)
- C.E. Knapp (Minneapolis), (1)
- C.I. Hood & Co. (Lowell, Mass.), 1904 (1)
- C.J. West (Minneapolis) (1)
- Calumet (Chicago) (1)
- Calumet Baking Powder Co (Chicago) (1)
- Calumet Baking Powder Co (Chicago, Ill, 1923) (1)
- Calumet Baking Powder Co. (Chicago) (1)
- Chas. E. Brown publishing company (Boston), 1905 (1)
- Clement's Print Shop (Waseca, Minnesota) (1)
- Cleveland Metal Products Co. (Cleveland, 1922) (1)
- Colman Manufacturing Co (Chicago) (1)
- Corn Products Refining Co (New York, N.Y) (1)
- Creamette Company (Minneapolis, Minnesota) (1)
- Cudahy Packing Co (1924) (1)