According to the National Postal Museum, the U.S. Post Office Department created the nation's commercial aviation industry. Between 1918 and 1927, it did so by "...[building] and [operating] the nation’s airmail service, establishing routes, testing aircraft and training pilots." After 1927, when the postal department turned the airmail service over to private contractors, federal dollars provided by financial base that helped commercial aviation get off the ground. Funds provided by airmail contracts allowed aviation companies to purchase larger and better airplanes, which were appropriate for passenger travel. When federal subsidies for airmail ended in 1952, the commercial aviation industry was well-established, featuring the DC-3 airplane.