- Amalgamated Meat Cutters and Butcher Workmen of North America, AFL-CIO3
- Ambrose E. Barnes & Bro.1
- American Association of University Women2
- American Bank Note Company1
- American Card Clothing Co.1
- American Copper Brass & Iron Works1
- American Documentary Films1
- American Dry Goods Company1
- American Electric Co.1
- American Glass Company1
- American Grocery Company4
- American Institute of Architects5
- American Institute of Architects. Detroit Chapter1
- American Institute of Architects. Florida Association1
- American Institute of Planners1
- American Iron Works Jones & Laughlins2
- American Listings, Inc.1
- American Mills1
- American Needle Co.1
- American Net & Twine Company1
- American Novelty Cloak Co.1
- American Pad & Textile Co.2
- American Rubber Co.2
- American Standard Jewelry Co.1
- American Supply Co.1
- American Surety Company6
- American System-Built (Firm)1,103
- American Tube & Stamping Co.1
- American Wholesale Corporation1
- Ames Cunehan and Newman, Inc.1
- Amherst College. Library1,634
- Amor Building Corp.1
- Ampir Realty Corp.1
- Anderson & Krum Stationery Co.2
- Anderson & Price1
- Anderson Avenue Park Plaza Corp.1
- Anderson Carriage Co.1
- Anderson Water, Light & Power Company1
- Anderson and Bremer1
- Anderson, Sargent & Co.1
- Andrew Apartments Inc.1
- Andrew Dutton1
- Andrew J. Joyce, Carriage Manufacturer1
- Andrews, Wayne1
- Angelo, G.1
- Anger-Brohel Co., Inc.1
- Angle, Edward H2
- Angotti, Thomas, 1941-1
- Angster, Blanche, 1874-195812
- Angster, Herbert, 1882-196512
- Anita Management Corp.1
- Annal Co.1
- Anomaly Films1
- Anru Realty Corp.1
- Ansel Adams Museum4
- Anshen & Allen1
- Ansie Realty Corp.2
- Ant Farm (Design group)4
- Anthony Campagna and Sons14
- Anthony Properties, Inc.1