 Third, Catron noted that the United States had respected the Sullivan Line in establishing the borders of the various territories north of Missouri.Justice Catron next attempted to construct the phrase "rapids of the Des Moines River" in an attempt to locate these rapids, as called for in federal legislation granting Missouri statehood and in the Missouri State Constitution of 1820.Iowa had claimed that the "Des Moines rapids" on the Mississippi River were the rapids referred to.