Signal Peak catches last light in the Kofa National Wildlife Refuge is located in Arizona in the southwestern United States, northeast of Yuma and southeast of Quartzsite. The refuge, established in 1939 to protect desert bighorn sheep, encompasses over 665,400 acres (2,693 km2) of the Yuma Desert region of the Sonoran Desert. Broad, gently sloping foothills as well as the sharp, needlepoint peaks of the Kofa Mountains are found in the rugged refuge. The small, widely scattered waterholes attract a surprising number of water birds for a desert area. A wide variety of plant life is also found throughout the refuge.