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- Pace Airlines (1996 - 2009)
- Pacific Air Lines (1958 - 1968, to Hughes Airwest)
- Pacific Air Transport (1926 - 1927)
- Pacific Alaska Airways (1973 - 1986)
- Pacific East Airlines (ceased operations 1984)
- Pacific Express (1982 - 1984)
- Pacific International - Las Vegas
- Pacific International - Oakland
- Pacific Nevada Airlines
- Pacific Southwest Airlines (PSA) (1945 - 1988, to USAir)
- Pan American Airways (1996–1998)
- Pan American Airways (1998–2004)
- Pan American-Grace Airways (Panagra) (1928 - 1967, to Braniff International Airways)
- Pan American World Airways (1927 - 1991)
- Pan Am Express (the airline purchased by Pan Am formerly known as Ransome Airlines)
- Paradise Island Airlines (1989 - 1997)
- Pennsylvania Central Airlines
- People Express (1981 - 1987, to Continental Airlines)
- Piedmont Airlines (1940 - 1989, to USAir)
- Pilgrim Airlines
- Pioneer Airlines (1946 - 1955, merged with Continental Airlines)
- Planet Airways (????- June 8, 2005, speculation only at this point in time)
- Potomac Air
- Presidential Airways (1985 - 1989)
- Primaris Airlines (2002-2009)
- Private Jet Expeditions (1989 - 1995)
- Pride Air (August 1985 - November 1985)
- Pro Air (1997 - 2000)
- Provincetown-Boston Airlines (1949 - 1989)
Read more about this topic: List Of Defunct Airlines Of The United States