- Adelaide A. Claflin Letters, 18841
- Adin B. Underwood Papers, 1861/19261
- Administration records collection, 1776/197623
- Admiral John Randolph Tucker Papers, 1865/18971
- Advisory Committee Research Collection, 1772/20178
- African American Family Photographs, 1880/19601
- African American man tintype portrait, 1865/19001
- Aileen Shafer, Collector, Material regarding African-Americans, 1829/18841
- Alabama Collection, 1823/18931
- Albert C. Swindler Papers, 1862/1929, bulk 1862/18641
- Albert Frederick Wilson papers, 1840/19342
- Albert R. Gallatin papers, 1795/18281
- Alderman family papers, 1779/19616
- Alexander Brown Papers (I), 1815/19108
- Alexander Brown Papers (II), 1748/190015