Douglas DC-3 American AirlinesAmerican Airlines Douglas DC 3. DC 3s delivered to US airlines before the nation became involved in World War II played a most important part in the development of reliable national air routes. It has been recorded that in the period 1936 1941 national passenger mileage in the US increased by almost 600 per cent, a growth that was very largely due to the DC 3, which was the primary airplane of most US airlines in this period. The DC 3's rugged