The stretch of Route 66 that passes through California extends from the Colorado River (Topock), near Needles, to the Pacific Ocean at Santa Monica Some 320 miles of Route 66 pass through California's deserts, mountains, metropolitan areas and beach communities. California's Route 66 is hard to beat as a travel theme for your next vacation. A pathway to California's history, cultural diversity, geology, geography and architecture, Route 66 in California reflects a significant part of our National Heritage.