Standing atop a recently painted yellow aviation arrow in the Pumpernickel Valley of remote Nevada, part of the arrow & beacon airmail system.  Before our current GPS satellite & radar, airplane pilots who did transcontinental airmail routes at night would fly following these large cement arrows, often accompanied by beacons with a light.  While there were over 1500 of them across the country back in the day, about 100 of them remain today, decaying & forgotten like this one.  This one is along the San Francisco to Salt Lake City airway, to which the route was established on September 8, 1920 & discontinued on November 30, 1930.