On a late summer day in September, the sound of cicadas pierced the profound silence in the sprawling grasslands and gently rolling hills of the San Rafael Valley in southern Arizona. But before long, the shrill buzzing gave way to the rumble of heavy machinery sculpting an unpaved road leading to the US-Mexico border.
In the distance, a deer darted across the road and disappeared into a thicket of oak trees. A few miles later, a fenced-in worker camp came into view, next to a construction site full of trucks, bulldozers and cranes.
