Cucamonga Peak is one of the highest peaks in the San Gabriel Mountains of California. The area is in the Cucamonga Wilderness on the San Bernardino National Forest. Named for Tiburcio Tapia's Rancho Cucamonga, the mountain towers over the present-day cities of Rancho Cucamonga, Ontario and Fontana. The peak can be seen west of Cajon Pass on Interstate 15, the route from Southern California to Las Vegas.