California Vehicle Code
Sec. § 110


Alley is any highway having a roadway not exceeding 25 feet in width which is primarily used for access to the rear or side entrances of abutting property; provided, that the City and County of San Francisco may designate by ordinance or resolution as an alley any highway having a roadway not exceeding 25 feet in width.
Source
Last accessed
Jun. 6, 2016