R.I. Gen. Laws § 2-13-2: Effective date as to future ratifications.

When the compact is ratified by any of the states of the United States that may legally join in the compact in accordance with the constitution and laws of that state or by any of the provinces of the dominion of Canada, in accordance with the laws of Canada, then the compact becomes operative and effective as between this state and that other state or states of the United States or provinces of the dominion of Canada.