- IAWA: International Archive of Women in Architecture Records, 1967/2013, bulk 1985/20081
- Independent Order of St. Luke Records, 1877/19703
- Inge Horton Architectural Collection, 1964/199936
- Institute for the History of Technology and Industrial Archaeology Records, 1875/2005, bulk 1980/200519
- International Association for Identification Records, 1842/2012, bulk 1910/195916
- Ira E. Robinson Papers, 1818/19301
- Ira E. Robinson Papers, 1869/19511
- Irvine-Saunders Family Papers
1745-1910 Inclusive16
- Isaac & Josiah Williams Brick Company, Account Books, 1844/19901
- Isaac B. Smith, Farmer and Music Teacher, Newspaper Clippings and Other Material, 1840/19841
- Isaac McNeel (b.1830) Papers, 1850/19081
- Isaac White Letters, 1861/19381
- Isabella Bain memory album, 1870/19131
- Isaiah Bolyard Family Scrapbook, 1880/19591
- Israel C. White (1848-1927) Papers, 1875/18881