Kingman Wash Trailhead is located in Lake Mead National Recreation Area, south of Hoover Dam, along Highway 93 on the Arizona side of the Colorado River, about 40 minutes southeast of Las Vegas.
From town, drive out towards Hoover Dam, then continue south on Hwy 93 into Arizona. Leave the highway at Exit 2 (Kingman Wash Road; Table 1, Site 0793), turn right and then right again, driving north back up along the highway on the frontage road for about 200 yards to a gate. Turn left into a large dirt parking area (Site 1420). Park here; this is the trailhead.
Link to trailhead map.