U.S. Army transfers mail to Post Office

Credit - United Airlines Archives

Curtiss JN-4H Jenny

Credit - Air Mail Pioneers

Boeing and Hubbard fly international airmail

Credit - Boeing Corporation

Standard mail plane

Credit - United Airlines Archives

De Havilland mail plane

Credit - United Airlines Archives

De Havilland 4B flying mail

Credit - United Airlines Archives

J.L.6 mail plane

Credit - Jesse Davidson Aviation Archives

Original transcontinental route

Credit - FAA

DH-4B in Omaha

Credit - U.S. Postal Service

Night-flying beacon

Credit - U.S. Air Force Museum

Test of light system in 1923

Credit - ") 2001 National Air and Space Museum, Smithsonian Institution (SI Videodisc No. A-32904)"