signboard, interesting place

Arrow used for navigation on the first air mail route between Los Angeles and Salt Lake CityIn the late 1920s and early 1930s, the new Aeronautics Branch in the Department of Commerce established a 650-mile air route from Los Angeles to Salt Lake City to carry mail. It was designated as Contract Air Mail Route 4 (CAM-4).Large concrete arrows were constructed on the ground along the way as visual navigational aids for the planes flying the mail route. There were built at intervals of approximately 10 miles and were about 70 feet long. Typically, there was a 51-foot beacon tower in the middle of the arrow topped with a powerful rotating beacon light. Below the rotating light were two course lights pointing forward and backward along the arrow. The course lights flashed a code to identify the beacon's number. A generator shed, where required, stood at the "feather" end of the arrow.Western Air Express was awarded the contract for the Los Angeles to Salt Lake route. Their first flight was made in April of 1926 in a Douglas M-2 airplane.The concrete arrows are all that remain today.Source: wchsutah.org/aviation/navigation-arrows.php