Jim Ray, The Story of American Aviation
“ A number of short lines operating routes from the Great Lakes and down through the south were soon to be merged to create American Airlines.In 1928, an air traveler making an extensive trip would be likely to fly in seven or eight different types of planes. He might step into a Fokker tri-motor, change to a single-engined Boeing, ride for some distance in a Ford tri-motor or a Whirlwind-powered Travel Air, and finish his trip in a Curtiss Carrier Pigeon. The planes usually flew low, at between one and two thousand feet. ”
