- Advisory Committee Research Collection, 1772/201713
- African and African American photograph collection, 1850/19451
- Aileen Shafer, Collector, Material regarding African-Americans, 1829/18845
- Alabama Collection, 1823/18932
- Albert Frederick Wilson papers, 1840/19343
- Albert R. Gallatin papers, 1795/18281
- Albert Taylor Bledsoe and Sophia Bledsoe Herrick letters, 1858/19081
- Alderman family papers, 1779/19617
- Alexander Brown Papers (I), 1815/191013
- Alexander Brown Papers (II), 1748/19008
- Alexander Family Papers
1800-18909
- Alexander Haight family collection, 1764/19766
- Alexander Hamilton, Jr. Letters, 1832/18331
- Alexander Jackson Davis architectural drawings, 1859/18705
- Alexander Lockhart Nelson papers, 1848/19021