- A.B. Stickney, Compiler, Genealogical Materials1
- A.C.L. Gatewood Papers1
- Abner Osburn, Physician, Papers1
- Adolphus DeBussey, Soldier, Civil War Letters4
- Adolphus P. Howard Papers2
- Aileen Shafer, Collector, Material regarding African-Americans1
- Alan Clarke Railroad Research Papers16
- Allen D. Frankenberry, Soldier, Civil War Diaries and Memoir1
- Allen Family Papers31
- Alpheus Garrison Civil War Records1
- Alston Gordon Dayton Papers2
- American Missionary Society Papers1
- Ancella Bickley, Historian, Research Papers regarding African-Americans33
- Andrew Delmar Hopkins Papers1
- Andrew Nelson Campbell (d.1919) Papers1