- Le Rouge, Georges-Louis3
- Leclerc, Jean, 1560-16213
- Leclerc, Jean, 1560-1621, cartographer3
- Leith, C. K. (Charles Kenneth), 1875-19563
- Lewis, Samuel, 1753 or 1754-18223
- Lizars, Daniel, 1760-18123
- Lobeck, A. K. (Armin Kohl), 1886-19583
- Lodge, John, -17963
- Longman, Rees, Orme, Brown, and Green3
- Lynch, F. C. C. (Francis Christopher Chisholm), 1884-3
- Mangum, A. W.3
- Marshall, R. B. (Robert Bradford), 1867-19493
- Maryland Geological Survey3
- Matthews-Northrup Works3
- McEvoy, James, 1862-3
- McGee, W J, 1853-19123
- McPherson, James Birdseye, 1828-18643
- Minnesota Transfer Board of Trade.3
- Minnesota. Division of Game and Fish3
- Mitchell, S. Augustus (Samuel Augustus), 1792-1868, cartographer.3