- Nordstrand, E.1
- Northern Oil Company1
- Northern Pacific Railway Company. Land Department1
- Nutter, Frank H., 1853-1932.1
- O'Hara and Zeese Civil engineers and Surveyors1
- Ogaard, Louis A.1
- Olesiak, Rachael A1
- Oliver Iron Mining Company (Duluth, Minn.). Mining Engineering Department.1
- Ozersky, Ted1
- Palka, Stephen1
- Papike, J. J. (James Joseph), 1937-20201
- Parham, Wallace E.1
- Paul Jacobs1
- Payne, C. M.1
- Pederson, R.1
- Petersen, Penny1
- Pezolt, F.1
- Phillips Petroleum Company1
- Phinney, William C.1
- Piegat, James1