US Contract Air Mail (CAM) routes. Looks like they have CAM #1 NYC to Boston and CAM #17 NYC to Chicago and also either CAM #13 or #15 Philadelphia to Washington D.C. They’re all part of the pre 1934 US air mail system which also had hundreds of concrete arrows and flashing beacons guiding the pilots
Check out this mod (which I may have a vested interest in ) , for some West Coast US air mail routes. And if I ever pull my thumb out, maybe some more in the future.
) , for some West Coast US air mail routes. And if I ever pull my thumb out, maybe some more in the future.