Boeing designed the Model 40 in 1927 and the four-seat 40B-4 derivative was used on the 1,918 mile air mail route from San Francisco to Chicago. The rugged aircraft had a 525 h.p. P&W Hornet powerplant. Obtained from United Airlines 60 years ago.
This photo was added on 17 September 2017, and has since been viewed 137 times.