- A.B. Stickney, Compiler, Genealogical Materials1
- A.C.L. Gatewood Papers1
- A.M. Scott Correspondence1
- Abner Osburn, Physician, Papers1
- Adolphus DeBussey, Soldier, Civil War Letters2
- Adolphus P. Howard Papers2
- Aileen Shafer, Collector, Material regarding African-Americans1
- Alan Clarke Railroad Research Papers16
- Albert M. Reese (1872-1965) Papers1
- Allen D. Frankenberry, Soldier, Civil War Diaries and Memoir1
- Allen Family Papers26
- Alpheus Garrison Civil War Records1
- Alston Gordon Dayton Papers4
- American Flint Glass Workers Union Papers1
- American Missionary Society Papers1