- Macmillan Co (New York) (1)
- Macoy Publishing and Masonic Supply Co (New York) (1)
- Macrae Smith (Philadelphia) (2)
- Madeira (5)
- Madison AIDS Support Network (1)
- Madison Association of Commerce (Madison, Wis) (1)
- Maggs Bros. Ltd. (London) (9)
- Magill-Weinsheimer Co. (1)
- Mahely-Lamy (Berne) (1)
- Maison Andriveau Goujon (1894-1900) (29)
- Majestic Publishing Company (Indianapolis, Indiana) (2)
- Major & Knapp Eng. Mfg. & Lith Co (New York) (1)
- Malleable Iron Range Co (Beaver Dam, Wis, 1925) (1)
- Mangum & Josephine Weeks (Alexandria) (1)
- Manhattan Post Card Company (New York, New York) (4)
- Mankyūdō (Edo, Japan) (2)
- Map branch, CIA (1)
- Maquet Gr. (1)
- Maquet, Gr. (1)
- Marcel Delboy (1)
