- Inge Horton Architectural Collection, 1964/199918
- Institute for the History of Technology and Industrial Archaeology Records, 1875/2005, bulk 1980/200512
- Interior and exterior photographs of Lee House, 1869/18701
- International Association for Identification Records, 1842/2012, bulk 1910/19595
- Invoice from Torsch and Rea Engravers (Baltimore, Md.), 18692
- Ira E. Robinson Papers, 1818/19301
- Ira E. Robinson Papers, 1869/19511
- Irvine-Saunders Family Papers
1745-1910 Inclusive14
- Isaac & Josiah Williams Brick Company, Account Books, 1844/19901
- Isaac B. Smith, Farmer and Music Teacher, Newspaper Clippings and Other Material, 1840/19841
- Isaac Horne Ledgers, 1824/18702
- Isaac McNeel (b.1830) Papers, 1850/19081
- Isaac R. Trimble letters, 1862/18701
- Isaac White Letters, 1861/19381
- Isabella A. Myler album, 1860/18691