- Adams Papers, 1782/18902
- Adele Goodman Clark papers, 1849/19784
- Adin B. Underwood Papers, 1861/19262
- Administration records collection, 1776/197626
- Admiral John Randolph Tucker Papers, 1865/189714
- Adolphus DeBussey, Soldier, Civil War Letters, 1861/1998, bulk 1861/18712
- Adolphus P. Howard Papers, 1850/19381
- Adolphus P. Howard Papers, 1854/19041
- Advisory Committee Research Collection, 1772/201714
- African American Stereoview Collection, 1860/19011
- African American man tintype portrait, 1865/19001
- African and African American photograph collection, 1850/19451
- Aileen Shafer, Collector, Material regarding African-Americans, 1829/18841
- Alabama Collection, 1823/18932
- Alan Clarke Railroad Research Papers, 1861/201216