There is created the Trident Economic Development Finance Authority. The jurisdictional area of the authority shall consist of two or more of the counties of Berkeley, Charleston, and Dorchester which counties qualified electors have each approved their participation in the authority by referendum. The governing body of the authority is a board of not more than seven members whose members shall serve for terms of four years and until their successors are elected and qualify. The governing bodies of Berkeley and Dorchester Counties shall each elect two members of the board and the governing body of Charleston County shall elect three members of the board upon approval of their county’s participation by referendum. Vacancies on the board must be filled for the unexpired term in the manner of the original election. The authority is a local political subdivision as contemplated by § 11-35-310(18).