What is the only US state that has rivers for both its western and eastern borders?

Iowa is bordered by the Mississippi River on the east; the Missouri River and the Big Sioux River on the west; the northern boundary is a line along 43 degrees, 30 minutes north latitude.

The southern border is the Des Moines River and a line along approximately 40 degrees 35 minutes north, as decided by the U.S. Supreme Court in Missouri v. Iowa after a standoff between Missouri and Iowa known as the Honey War.

Iowa has 99 counties, but 100 county seats because Lee County has two. The state capital, Des Moines, is located in Polk County.

https://en.wikipedia.org/wiki/Iowa