N.J. Stat. Ann. § 40:20-35.1

The board of chosen freeholders in all counties governed by article 3, chapter 20 of Title 40 of the Revised Statutes as of January 1, 1966, shall consist of 7 members to be elected by the voters of the county at the general election next following the effective date of this act. At the said election there shall be elected 2 members for 1 year, 2 members for 2 years and 3 members for 3 years and the ballots shall designate which members are to serve for the terms of 1, 2, and 3 years respectively. At succeeding elections, all members shall be elected for a term of 3 years.