- Marken, William J.1
- Marschner, Francis, 1882-19661
- Marsden, William, 1754-18361
- Marshall County Land Co. (Warren, Minn.)1
- Marshall, R. B. (Robert Bradford), 1867-19491
- Martin, Christopher1
- Martin, Ralph (Delineator)1
- Martin, Ronald E.1
- Maryland. Conservation Department.1
- Maryland. Weather Service1
- Mason, Charles, 1728-17861
- Massachusetts. Department of Public Health1
- Massachusetts. Metropolitan Park Commission1
- Mathez, E.A.1
- Matson, H. C.1
- Mattson, L. A. (Lewis Arthur), 1931-1
- Mavila, Oscar1
- Maxima (Firm)1
- Mayewski1
- McCartan, Lucy1