Chouteau Island and Gateway Arch can both be found having at least half of their area in what state?
Chouteau Island: Chouteau Island ( ), situated approximately 8 mi due north of the Gateway Arch in St. Louis, Missouri, and approximately 1 mi south of the confluence of the Missouri River and Mississippi River, is one of a cluster of three islands: Chouteau Island, Gabaret Island, and Mosenthein Island. Chouteau Island:  Most of Chouteau Island lies in Chouteau Township, but its southern quarter lies in Venice Township, both in Madison County. Gateway Arch: The Gateway Arch is a 630 ft monument in St. Louis in the U.S. state of Missouri.
Missouri