 Street routings in San Francisco are more commonly referred to by their street names rather than the route number.Portions of the route between Southern California and the Bay Area are named El Camino Real or El Camino Real Freeway, but such names are rarely used colloquially; the route number is used instead.In Northern California the section of US 101 between Sonoma and Marin counties is often referred to as the Novato Narrows because of the reduction from six lanes to four.