| Albemarle Corporation | business, enterprise, public company | Baton Rouge | 1994 |
| Albert Einstein College of Medicine | university, organization | — | 1955 |
| Albertsons | supermarket chain, business, enterprise, public company | Boise | 1939 |
| Albertus Magnus College | private not-for-profit educational institution, school | — | 1925 |
| Alcon Entertainment | business, enterprise | Los Angeles | 1997 |
| Alcorn State University | historically black college or university, public educational institution of the United States, school, university, census-designated place in the United States, land-grant university | — | 1871 |
| Allen-Bradley | business, public company | Milwaukee | 1903 |
| AllianceBernstein | business, enterprise, public company | Nashville | 1967 |
| Alliant Techsystems | enterprise, public company, aerospace manufacturer | Arlington County | 1990 |
| Allis-Chalmers | business | Milwaukee | 1901 |
| Allison Engine Company | business | Indianapolis | 1915 |
| Allstate | business, enterprise, public company | Northbrook | April 17, 1931 |
| Ally Financial | bank, business, enterprise, credit institution, public company | Detroit, New York City | 1919 |
| Alpha Tomo Global Resoures Sdn Bhd | business, temporary work agency, enterprise, public company | Milwaukee | 1948 |
| Amazon Robotics | business | Massachusetts | January 1, 2003 |
| Amazon Web Services | platform as a service, hyperscaler, internet hosting service, computing platform, business | Seattle | March 2006 |
| Amblin Entertainment | television production company, animation studio, film production company | Universal City | 1981 |
| Amblin Television | business | Universal City | July 31, 1984 |
| AMC Global Media | public company | New York City | 1980 |
| Amdahl Corporation | business | Sunnyvale | October 19, 1970 |
| Ameren | holding company, public company | St. Louis | 1997 |
| America West Airlines | airline | Tempe | 1981 |
| American Academy in Rome | nonprofit organization, educational institution, research center | Rome, New York City | 1894 |
| American Academy of Arts and Sciences | nonprofit organization, learned society, academic publisher | Cambridge | May 4, 1780 |
| American Airlines | airline, public company | Fort Worth | April 15, 1926 |
| American Antiquarian Society | research library, nonprofit organization, historical society, learned society | Worcester | 1812 |
| American Association for the Advancement of Science | nonprofit organization, open-access publisher, international organization, academic publisher | Washington, D.C. | September 20, 1848 |
| American Association of Petroleum Geologists | voluntary association, academic publisher | — | 1907 |
| American Concrete Institute | organization, academic publisher | Farmington Hills | 1904 |
| American Conservatory Theater | theatre company, nonprofit organization, private not-for-profit educational institution | San Francisco | 1965 |
| American Cyanamid | business | Wayne | 1907 |
| American Eagle Outfitters | business, brick and mortar, public company | Pittsburgh | 1977 |
| American Economic Association | organization, open-access publisher, scientific society | Nashville | 1885 |
| American Geophysical Union | nonprofit organization, open-access publisher, scientific society | Washington, D.C. | 1919 |
| American Hockey League | professional sports league | — | 1936 |
| American Institute of Aeronautics and Astronautics | professional society, academic publisher | Reston | 1963 |
| American LaFrance | business, enterprise | Summerville | 1873 |
| American Library Association | nonprofit organization, open-access publisher, professional association, library association, academic publisher | Chicago | October 6, 1876 |
| American Locomotive Company | business | Schenectady, New York City | June 24, 1901 |
| American Numismatic Association | nonprofit organization, library, learned society | Colorado Springs | 1891 |
| American Physical Society | nonprofit organization, publishing house, open-access publisher, scientific society, learned society | College Park | May 20, 1899 |
| American Psychological Association | regulatory college, nonprofit organization, publishing house, open-access publisher, professional association, school accreditor | Washington, D.C. | July 1892 |
| American Radiator Building | skyscraper, hotel | — | 1924 |
| American Society for Testing and Materials | standards organization, business, company, learned society | West Conshohocken | 1961 |
| American Society of Civil Engineers | engineering society, regulatory college, professional association, academic publisher | Reston | 1852 |
| American Society of Mechanical Engineers | engineering society, regulatory college, organization, academic publisher | New York City | 1880 |
| American Sociological Association | nonprofit organization, learned society, academic publisher | 1430 K Street | 1905 |
| American Type Founders | type foundry, business | Elizabeth | 1892 |