Site Navigation Baja California California Colorado Idaho Hawaii Nevada New Mexico Oregon Utah Washington Wyoming     California 1 North - San Mateo County Index to California 1: Index Northbound Orange County Los Angeles County Ventura County Santa Barbara County San Luis Obispo County Monterey County Santa Cruz County San Mateo County San Francisco County Marin County Sonoma County Mendocino County Southbound Mendocino County Sonoma County Marin County San Francisco County San Mateo County Santa Cruz County Monterey County San Luis Obispo County Santa Barbara County Ventura County Los Angeles County Orange County Business Routes - list of all California 1 business routes California 1 north Erroneous Interstate 1 shield at the Westlake-Daly City/John Daly Boulevard onramps onto Northbound Interstate 280 and Northbound California 1. This is a set of contractor signs, so they were not placed by Caltrans. Photo taken 04/07/01 by Joel Windmiller. Page Updated June 29, 2009.