The United Aircraft and Transport Corporation was formed in 1929, when William Boeing of Boeing Airplane & Transport Corporation teamed up with Frederick Rentschler of Pratt & Whitney to form a large, vertically-integrated, amalgamated firm, uniting business interests in all aspects of aviation—a combination of airframe and aircraft engine manufacturing and airline business, to serve all aviation markets, both civil aviation (cargo, passenger, private, air mail) and military aviation.
After the Air Mail scandal of 1934, the U.S. government concluded that such large holding companies as United Aircraft and Transport were anti-competitive, and new antitrust laws were passed forbidding airframe or aircraft engine manufacturers from having interests in airlines.
This law forced United Aircraft and Transport to split into three separate companies.
The western manufacturing interests (including Northrop, formerly Avion Corporation), became Boeing Airplane Company, headquartered in Seattle.
The airline interests were merged into a single company, United Air Lines, Inc.,[2] headquartered in Chicago.