the dc-1 was followed by the delivery of 32 douglas dc-2s that started operations in may 1934 on twa's columbus-pittsburgh-newark route. most were phased out by 1937 as the douglas dc-3 started service, but several dc-2s would be operational through the early years of world war ii. twa started using the dc-3 on june 1, 1937. the fleet included ten dst sleeper aircraft and eight standard dc-3 day versions.