The standard airliner of the late 1930 ’ s, the DC - 3, carried just 21 passengers at a cruising speed of 170 miles per hour [270 kph]; but after World War II, commercial airplanes grew much larger and more powerful, achieving cruising speeds of over 300 miles per hour [480 kph].
१९३९ के अंत तक, हवाई सफर इतना लोकप्रिय हो गया था कि अमरीकी एअरलाइनें साल में करीब ३० लाख सवारियाँ ढो रही थीं ।