55 ILCS 5/5-1004: Exercise of corporate powers.

The powers of the county as a body corporate or politic, shall be exercised by a county board, to wit: In counties under township organization (except the County of Cook), by the county board members elected under Division 2-3; in the County of Cook, by a board of county commissioners, pursuant to Section 3 of Article VII of the Illinois Constitution; in counties not under township organization, by the board of county commissioners.