Smithsonian Institution
National Air and Space Museum: America by Air: Airline Expansion and Innovation
Air travel grew in the 1920s and 1930s despite the Great Depression. Read about the new commercial airlines of the time and what it was like to fly at the dawn of commercial passenger flight.
National Academy of Engineering
Greatest Achievements: Airplane
This page provides an overview of the history behind one of the greatest engineering innovations of all time:the airplane. There is also a timeline showing its development.