In the late 1920s and early 1930s, the Post Office and Department of Commerce constructed large concrete arrows on the ground as visual navigational aids for planes flying the transcontinental mail routes. In the day time the arrows, spaced at about 10 mile intervals, pointed the pilots to the next arrow. Beacons situated next to the arrows provided night-time guidance. This is Summit or Beacon Hill light, number 38.
Historical, Transportation - Aviation