California Code, Vehicle Code - VEH § 25106

(a) Any motor vehicle may be equipped with lighted white or amber cowl or fender lamps on the front. Any vehicle may be equipped with not more than one amber side lamp on each side near the front, nor more than one red side lamp on each side near the rear. The light source of each such lamp shall not exceed four standard candlepower.

(b) Lamps meeting requirements established by the department for side-marker or combination clearance and side-marker lamps may be installed on the sides of vehicles at any location, but any lamp installed within 24 inches of the rear of the vehicle shall be red, and any lamp installed at any other location shall be amber.