| M-1/M-2/M-3/M-4 | |
|---|---|
| |
| Role | Single-seat mailplanes |
| Manufacturer | Douglas Aircraft |
| First flight | 1925 |
| Introduction | 1926 |
| Primary users | United States Post Office Western Air Express National Air Transport Inc |
| Number built | 57 |
The Douglas mailplanes were a family of 1920s American single-seat mail planes designed and built by the Douglas Aircraft Company. The aircraft were used to run the main routes of the United States Air Mail service until the introduction of three-engined aircraft in 1928.