Missouri constitution
Article III: legislative department
Section 39(e)

The general assembly is authorized to permit
upon the Mississippi and Missouri Rivers only, which shall include artificial spaces
that contain water and that are within 1000 feet of the closest edge of the main channel
of either of those rivers, lotteries, gift enterprises and games of chance to be conducted
on excursion gambling boats and floating facilities. Any license issued before or after
the adoption date of this amendment for any excursion gambling boat or floating facility
located in any such artificial space shall be deemed to be authorized by the General
Assembly and to be in compliance with this Section.