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- Mackey Airlines (1957 - 1981)
- Maddux Air Lines (1927 - 1929, to Transcontinental Air Transport)
- Mahalo Air (1993 - 1997)
- Mall Airways (1973 - 1989, to Business Express)
- Marine Airways (1936 to 1939) to Alaska Coastal Airlines
- MarkAir (1947 - 1995)
- Marquette Airlines (1930s - 1940s, to Trans World Airlines)
- MAXjet (2005 - 2007)
- Mayflower Airlines (1936 - 1945)
- McClain Airlines (1987-1987)
- Mesaba Airlines (1942 - 2012)
- MetroJet (1998 - 2001)
- Mexus Airlines
- MGM Grand Air (1987 - 1995, to Champion Air)
- MidAtlantic Airways (2002 - 2006)
- Mid-Continent Airlines (1928 - 1952, to Braniff)
- Mid Pacific Air (1981 - 1988)
- Mid-State Airlines (1964 - 1989, to Sentry Airlines)
- Midway Airlines (1979 - 1991 and 1993 - 2003)
- Midwest Airlines (1948-2010 to Frontier Airlines)
- Mississippi Valley Airlines (1969 - 1985)
- Modern Air Transport (1946-1975)
- Mohawk Airlines (1952 - 1988, to Allegheny Airlines)
- Morris Air (1992 - 1994, to Southwest Airlines)
- Mountain Air Express (1996 - 1998, to Air Wisconsin)
- Mountain West Airlines-Idaho (1979-1981)
- Mountain West Airlines (1995 - 1997 to Mesa Airlines)
- Muse Air (1982 - 1985, to Southwest Airlines)
Read more about this topic: List Of Defunct Airlines Of The United States