N.J. Stat. Ann. § 40:33-2

No such library shall be established until assented to by the legal voters of the county at any election at which the question of the establishment thereof shall be submitted. In counties which have heretofore adopted the provisions of an act entitled "An act to provide for the establishment and maintenance of county free libraries," approved April seventh, one thousand nine hundred and twenty, the referendum election provided for herein need not be held and the provisions of this article shall apply to such counties.