Pub. Util. Code, § 99502

(a) The tax may be imposed by the adoption of an ordinance by a taxing entity if (1) it calls a special election for the submission of a proposition to grant it the authority to impose the tax pursuant to the ordinance and (2) two-thirds of the voters voting at the special election approves the proposition. The special election may be held only when consolidated with an otherwise scheduled state election or local election for an area that includes the area under the jurisdiction of the taxing entity. In the case of the City of Los Angeles, it may call the special election only after securing the approval of the Los Angeles County Metropolitan Transportation Authority.

(b) Where two or more taxing entities have jurisdiction over the same area and are authorized pursuant to subdivision (a) to impose the tax under this chapter, the tax shall be imposed only by the taxing entity with the largest area under its jurisdiction.