Mo. Rev. Stat. § 210.580: Compact binding, when.

The compact shall become binding upon the state of Missouri upon legislative enactment of the compact into law by no less than thirty-five of the states. The initial effective date shall be the later of August 28, 2007, or upon enactment into law by the thirty-fifth jurisdiction*. Thereafter it shall become effective and binding as to any other compacting state upon enactment of the compact into law by that state.