Google, IBM & Meta Certificates – 40% Off
One plan covers every Professional Certificate on Coursera.
Unlock All Certificates
Explore the fascinating history behind thousands of massive concrete arrows scattered across the American landscape in this 10-minute documentary video. Discover how these mysterious 70-foot-long concrete structures, now abandoned in deserts, forests, and mountaintops, were once crucial components of America's pioneering airmail delivery system in the 1920s. Learn about the ambitious federal infrastructure project that created a nationwide network of rotating beacon towers and giant directional arrows to guide pilots through invisible highways in the sky before the advent of radar and GPS technology. Uncover the operational mechanics of this early aviation navigation system, understand the reasons behind its eventual abandonment, and find out where these forgotten relics of American aviation history can still be located today.
