- A.S. Hammack papers, 1864/19541
- Abbie Louisa Hill Scrapbook, 1874/18842
- Abner Osburn, Physician, Papers, 1846/19011
- Abolitionist Movement Collection, 1834/18882
- Abraham Lincoln Collection, 1860/19651
- Abraham Rudisill diary, 1875/18862
- Account Books, 1782/18952
- Accounts, 19th Century, 1836/18971
- Acker Family Diaries, 1880/19063
- Ackerly Family Papers4
- Adalbert J. Volck Collection of Etchings, 1861/19793
- Adam Empie Papers, 1811/2004, bulk 1811/18503
- Adams Papers, 1782/18902
- Adelaide A. Claflin Letters, 18842
- Adele Goodman Clark papers, 1849/19784