| Lowepro | Petaluma | 1967 |
| Lycoming | Williamsport | 1845 |
| M&T Bank | Buffalo | 1856 |
| M-Audio | Cumberland | 1998 |
| Mack Trucks | Allentown, Greensboro | 1900 |
| Macromedia | São Francisco | 25 de fevereiro de 1992 |
| Macy's, Inc. | Cincinnati, Macy's Herald Square | 1929 |
| Mailchimp | Ponce City Market | 2001 |
| Major League Soccer | Pennsylvania Plaza | 17 de dezembro de 1993 |
| MakerBot Industries | Nova Iorque | 20 de janeiro de 2009 |
| Manpower | Milwaukee | 1948 |
| Marmot | Santa Rosa | 1974 |
| Marriott Internacional | Bethesda | 8 de outubro de 1993 |
| Marsh & McLennan Companies | Nova Iorque | 1905 |
| Martin Marietta | Bethesda | 1961 |
| Marvel Entertainment | Nova Iorque | junho 1998 |
| Masten Space Systems | Mojave | 2004 |
| Match Group | Kerrville | 2009 |
| Matson, Inc. | Honolulu | 1882 |
| Mattel | El Segundo | janeiro 1945 |
| Maybelline | Nova Iorque | 1915 |
| McCormick & Company | Hunt Valley | 1669 |
| McGraw-Hill Education | Nova Iorque | 1888 |
| McIntosh Laboratory | Binghamton, Nova Iorque | 1949 |
| McKesson Corporation | Irving | 1994 |
| Mead Johnson | Glenview | 1905 |
| Memorex | Cerritos | 1961 |
| Mentor Graphics | Wilsonville | 1981 |
| Meraki | São Francisco | 2006 |
| Mercer Automobile Company | New Britain | 1909 |
| Merrell | Rockford | 1981 |
| Metro Pictures Corporation | Los Angeles | 1915 |
| MGA Entertainment | Los Angeles | 1979 |
| Microchip Technology | Chandler | 1989 |
| MicroStrategy | Tysons Corner | 1989 |
| Middle-earth Enterprises | Berkeley | 2022 |
| Midway Games | Chicago | 1988 |
| Milton Bradley Company | East Longmeadow | 1860 |
| Milwaukee Electric Tool Corporation | Brookfield | 1924 |
| MIPS Technologies | Sunnyvale | 1984 |
| Missouri Pacific Railroad | St. Louis | 1917 |
| Mobil Oil | Fairfax | 1966 |
| Moderna Therapeutics | Cambridge | 2010 |
| Molex | Lisle | 1938 |
| MoneyGram | Dallas | 1940 |
| Mopar | Chrysler Headquarters and Technology Center | 1933 |
| Morningstar, Inc. | Chicago | 1984 |
| MOS Technology | Norristown | 1969 |