- Madison, James ~ Papers ~ 1723-1836
- Manuscript Division ~ Selected Highlights
- Maps and Cartographic Items ~ 1500-Present
- Maritime Westward Expansion ~ Multiformat ~ 1820-1890
- McKinley, William, and Pan-American Exposition ~ Films ~ 1901
- Moldenhauer Archives ~ Musical Documents ~ 1000-1987
- Morse, Samuel F. B. ~ Papers ~ 1793-1919