Upon the adoption of the resolution of consent by the city, such street or portion thereof within the city shall thereupon constitute a county highway. A certified copy of such resolution shall be filed with the board of supervisors. When the city council relinquishes an existing city street to the county, a certified copy of such resolution shall be recorded; and upon such recordation, all right, title and interest of the city in and to such portion of the city street shall vest in the county.
Ca. Sts. and High. Code § 1723