California Code, Business and Professions Code - BPC § 5271

Except as otherwise provided in this chapter, the provisions of this chapter apply only to the placing of advertising displays within view of highways located in unincorporated areas of this state, except that the placing of advertising displays within 660 feet from the edge of the right-of-way of, and the copy of which is visible from, interstate highways or primary highways, including the portions of such highways located in incorporated areas, shall be governed by this chapter.