- Lewis, Warner, 1805-18881
- Lipman, Louis1
- Lloyd, James T.1
- Long, Stephen H. (Stephen Harriman)1
- Lowe, R. P.1
- Lyell, Charles, Sir, 1797-18751
- Mackay, Bertram Reid, 1885-1
- Mackenzie, Alexander, 1844-19211
- Macomb, J. N. (John N.), 1810 or 1811-18891
- Macpherson, Alexander1
- Magnuson, C. A1
- Mahlo, Emil, 1851-1904.1
- Martin, Ebenezer (Engraver)1
- Martin, Ronald E.1
- McKinley Publishing Co1
- McKinley Publishing Company1
- Mendenhall, Edward1
- Miller, Joseph G.1
- Minneapolis, St. Paul & Sault Ste. Marie Railway Company1
- Minnesota School of Mines Experiment Station1