Commercial aviation companies sought airmail contracts to subsidize their industry as manufacturers worked to integrate safety and passenger space into aircraft design. Early airmail legislation gave companies the financing they needed to build their industry.
Each company strove to produce the best aircraft for their needs. At this time, aircraft manufacturers could control their own aviation companies, and many did. Early airplane manufacturing companies included Curtiss-Wright, Glenn Martin, Boeing, Douglas, Ryan, Fokker, Ford, General Motors, Lockheed, Northrop and McDonnell. Some of these early manufacturers left the field altogether, others merged to form new companies focusing on the production and service ends of the airline industry.
In 1920, of the 328 aircraft produced in the U.S., 256 had been built for the military, and only 72 for civilian use. By 1927, the year that commercial aviators took complete control of airmail service, two thirds of the 1,495 airplanes built were for the commercial aviation industry.