- Ada Haldeman Ford, Suffragist, Papers, 1900/19701
- Adalbert J. Volck Collection of Etchings, 1861/19791
- Adam Empie Papers, 1811/2004, bulk 1811/18501
- Adam Finch Collection, 1891/19331
- Adam T. Finch Papers, 1895/19261
- Adamston Flat Glass Factory, Glass Cutting Tool, 1910/19301
- Adele Blow Chatfield-Taylor family papers, 1899/19771
- Adele Goodman Clark papers, 1849/19781
- Adin B. Underwood Papers, 1861/19261
- Administration records collection, 1776/19761
- Adolphus DeBussey, Soldier, Civil War Letters, 1861/1998, bulk 1861/18711
- Adolphus P. Howard Papers, 1850/19381
- Advertisement Trade Card for "Quignon-Rombach", 1880/19201
- Advisory Committee Research Collection, 1772/20171
- African American Family Photographs, 1880/19601