In the years following World War I, in response to pilots of the fledgling airmail service getting lost, and often crashing, the government built a network of giant concrete arrows and beacons that would lead the pilots safely along their route. Many of the arrows survive to this day, and can be seen here via Google Maps.

arrow-sloan

This arrow is near the Sloan mine, pointing Northeast towards Las Vegas. The M Hotel can be seen in the distance (Photo Credit: Matt Adams/8 News NOW).

Minimize Info