- American Political Items Collectors collection3
- American Public Transportation Association records, 1898/19996
- American Rhododendron Society Records, 1927/20221
- Ancella Bickley, Historian, Research Papers regarding African-Americans, 1775/2018, bulk 1970/20118
- Ann A. Hertzler Collection, 1863/2013, bulk 1974/20001
- Anna P. Sokolina Architectural Collection, 1924/20191
- Anna Schein, Collector, Feedsack Textile Bag Collection, 1925/19656
- Anne H. Cutler Papers, 1930/2013, bulk 1954/20002
- Anne T. Chapman Papers, 1884/19541
- Annual Reports (PB-02), 1935/20181
- Appalachian Prints Collection, 1839/2010, bulk 1859/19092
- Archibald W. Campbell (1839-1899), Newspaperman, Papers, 1855/1941, bulk 1855/18991
- Architectural League of New York: Archive of Women in Architecture Records, 1892/19761
- Armistead Boothe Papers (MS164), 1803/19901
- Armistead-Cocke Papers, 1680/19171