Rockford Mayor Tom McNamara announced on Monday that he is resigning from that position at the end of August to become CEO of the Illinois Municipal League.
The non-profit lobbying association represents the nearly 1,300 municipalities in the state.
McNamara will replace Brad Cole, who began as IML CEO in December 2014.
Cole told the State Journal-Register he announced his retirement plans three years ago and plans to depart at the end of the year.