American had a direct role in the development of the DC-3, which resulted from a marathon telephone call from American Airlines CEO C. R. Smith to Donald Douglas, when Smith persuaded a reluctant Douglas to design a sleeper aircraft based on the DC-2 to replace American's Curtiss Condor II biplanes. (The existing DC-2's cabin was 66 inches (1. 7 m) wide, too narrow for side-by-side berths. ) Douglas agreed to go ahead with development only after Smith informed him of American's intention to purchase 20 aircraft. The prototype DST (Douglas Sleeper Transport) first flew on December 17, 1935, (the 32nd anniversary of the Wright Brothers' flight at Kitty Hawk). Its cabin was 92 in (2. 3 m) wide, and a version with 21 seats instead of the 14–16 sleeping berths of the DST was given the designation DC-3. There was no prototype DC-3; the first DC-3 built followed seven DSTs off the production line and was delivered to American Airlines. American Airlines inaugurated passenger service on June 26, 1936, with simultaneous flights from Newark, New Jersey and Chicago, Illinois.