40 ILCS 5/14-134.1
The 2 elected trustees shall be elected, beginning in 1986 and every 5 years thereafter, for a term of 5 years beginning July 15 next following their election. The trustees to be elected under Section 14-134 of this Code in accordance with this amendatory Act of the 96th General Assembly shall be elected within 90 days after the effective date of this amendatory Act of the 96th General Assembly for a term of 5 years after the effective date of this amendatory Act. Trustees shall be elected every 5 years thereafter for a term of 5 years beginning July 15 next following their election. Elections shall be held on May 1, or on May 2 when May 1 falls on Sunday. Candidates for the contributing trustee shall be nominated by petitions in writing, signed by not less than 400 contributors with their addresses shown opposite their names. Candidates for the annuitant trustee shall be nominated by petitions in writing, signed by not less than 100 annuitants with their addresses shown opposite their names.
If there is more than one qualified nominee for either elected trustee, the board shall conduct a secret ballot election by mail for that trustee, in accordance with rules as established by the board.
If there is only one qualified person nominated by petition for either trustee, the election as required by this Section shall not be conducted for that trustee and the board shall declare such nominee duly elected.
A vacancy occurring in the elective membership of the board shall be filled for the unexpired term by the board.
40 ILCS 5/14-134.1