The Missouri River and its tributary, the Big Sioux, form the western border of Iowa.
The two rivers that partially form the eastern boundary of the United States are the Mississippi River and the St. Lawrence River. The Mississippi River flows southward from Minnesota to the Gulf of Mexico, serving as a significant boundary for several states. The St. Lawrence River, situated in the northeastern part of the country, forms part of the boundary between the United States and Canada.
Two rivers partially form Illinois State's Eastern boundary. The Wabash River is one river that forms Illinois' boundary. The Ohio River is the other river that forms the state's boundary.
Mississippi
It is the Danube River.
The Mississippi River forms the Western border of the States of Illinois, Tennessee, and Mississippi. The Mississippi River forms the Eastern border of the States of Iowa, Missouri, Arkansas, and Louisiana.
Mississipi-Missouri
The Ural Mountains,the Ural river,and the Caspian Sea.
Missouri eventually enter the Mississippi river which then leads to the gulf of Mexico
The Mississippi River forms the western border of Illinois.
The Minnesota River runs into the Mississippi. So do the Missouri, Illinois, and Ohio Rivers.
Red River