The 1887 Sonora earthquake dislodged massive boulders lining the canyon walls, which came to rest in the valley below. In 1905 the newly created U.S. Forest Service began administering Sabino Canyon. During the Great Depression, the Works Progress Administration (WPA) and Emergency Relief Administration (ERA) built Sabino Dam and nine bridges over Sabino Creek in an attempt to build a road to the top of Mount Lemmon. The road travels about 4.5 miles into the canyon, but was not completed due to the steep terrain at the end of the canyon.