New Jersey Statutes Title 40. Municipalities and Counties 40 § 54-29.10

The board of trustees of such joint library shall consist of (a) the mayor or other chief executive officer of each participating municipality;  (b) the superintendent of schools of the local school district of each such municipality, or, if there be no such official, one of the principals in the local school system, selected by the mayor or other chief executive officer, or, if there be neither of such officials, the president of the board of education;  and (c) three citizens to be appointed by the mayor or other chief executive officer of each such municipality, at least two of whom shall be residents of the municipality.  The initial appointments of such citizen members shall be for terms of three, four and five years, respectively, as they may be selected by the mayor or other chief executive officer.  Thereafter, such citizen appointments shall be for terms of five years and until their successors are appointed and qualify.  The original citizen appointments in any municipality having a free public library at the time for the formation of the joint library shall be made from among the appointed citizen members of the board of trustees of such library.  Vacancies occurring on the board of trustees shall be filled for the unexpired term only.  The mayor or other chief executive officer and the superintendent of schools or the principal, as the case may be, serving as a member of the board, may, respectively, appoint an alternate to act in his place with authority to attend all meetings of the board and in his absence, to vote on all questions before the board.