- 17 Allegheny Avenue
- 1 Allegheny Avenue Dye Works-Masland, C.H. & James
- 6 Allegheny County, Pennsylvania
- 1 Allegheny Hosiery Co.
- 1 Allegheny House
- 1 Allegheny Theatre
- 28 Allegheny West, Pennsylvania
- 1 Allegorical prints
- 1 Allegories (document genre)
- 7 Allegory
- 1 Allen & Hanburys
- 2 Allen Grove Female Seminary
- 1 Allen, H.R. Coal & Lumber Yard
- 1 Allen, John see Brice, William & Allen, John
- 2 Allen, John D., Architect
- 1 Allen, Richard, 1760-1831
- 1 Allen, Viola, 1867-1948
- 2 Allen, William Chief Justice of the Province of Pennsylvania
- 1 Allen, William H. (William Henry), 1808-1882
- 4 Allens Lane
- 1 Allen's Lane Art Center
- 5 Allentown, Pennsylvania
- 28 Alleys
- 3 Allies
- 4 Alligators
- 1 Allison Street
- 1 Allison, Joseph, 1819-1896
- 1 Allison's Clothing
- 5 Alma Street
- 4 Almanacs
- 1 Almeda Mills
- 17 Almond Street
- 1 Almond's Cotton Factory
- 66 Almshouses (buildings)
- 1 Alpaca (fiber)
- 17 Alphabet books
- 124 Alphabets
- 1 Alphington, England
- 1 Alphonso Faber (Firm)
- 1 Alpine (Alps)
