The Mississippi River.
The Mississippi River borders Iowa on the eastern side, separating it from Illinois and Wisconsin. The Missouri River borders Iowa on the western side, separating it from Nebraska and South Dakota.
Iowa is bordered by the Mississippi River on the east and the Missouri River and the Big Sioux River on the west.
The states of Iowa, Missouri, and Arkansas have their eastern borders on the Mississippi River. The Mississippi River borders seven other states.
Portions of the borders of South Dakota, Iowa, Nebraska, Kansas, and Missouri follow what was at one time the Missouri River's course. The river no longer follows the exact same path it did when the borders were established, so the borders are no longer coincident with the river itself in all places.
There is no one body of water which borders all of those states. The Missouri River travels through North Dakota and South Dakota, then borders Nebraska and Iowa and part of Kansas and Missouri before it travels through the state of Missouri and joins the Mississippi River. The Red River borders Texas and Oklahoma and then travels through Arkansas and Louisiana before it joins the Mississippi River. The Red River of the North borders North Dakota and Minnesota. The Mississippi River travels through Minnesota and borders Iowa, Missouri, Arkansas, and Louisiana.
the James river
The longest rivers in Iowa are the Missouri River and the Mississippi River, which form the state's western and eastern borders, respectively. The Des Moines River is the longest river entirely within Iowa, flowing approximately 525 miles. Other significant rivers include the Cedar River and the Iowa River, both of which contribute to the state's extensive river system.
Iowa borders Missouri to the south.
Loess Hills
One of the three rivers that border Iowa is the Mississippi. The other two rivers that border the state are the Missouri river, and the Big Sioux river.
The west side of the Mississippi River borders Iowa, Missouri and Arkansas.