Source: American Airlines.
The DC-3, introduced in 1935, was one of the first reliable and low-cost aircraft able to transport 21 passengers with a crew of 3. By 1938, it carried 95% of all American air traffic. The above American Airlines DC-3 is labeled a “Flagship Skysleeper” because long-distance services, such as transcontinental flights, were often organized overnight with passengers able to use small bunk beds.