California Vehicle Code definition of
Alley
CVC Section 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.