45 ILCS 78/40

(a) The states of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin are eligible to join this compact. Upon approval of the Commission, according to its bylaws, other states may also be declared eligible to join the compact. (b) As to any eligible party state, except as provided in subsection (c), this compact shall become effective when its legislature shall have enacted the compact into law. (c) This compact shall not become initially effective until enacted into law by any 3 party states incorporating the provisions of this compact into the laws of those states. Amendments to the compact shall become effective upon their enactment by the legislatures of all compacting states.