The eastern border of the state is marked by the Mississippi River which runs between Iowa and Illinois. The western border is marked by the Missouri and Big Sioux rivers. The northern border is a line 43 degrees, 30 minutes north latitude. The southern border follows the northern border of Missouri. Iowa and Missouri disagreed about the location of the Iowa-Missouri border. This argument was ended by the Supreme Court of the United States in the 1896 case, "State of Missouri v. State of Iowa", after a standoff called the Honey War. The border follows the Des Moines River for the far eastern part of the state and is at close to 40 degrees, 35 minutes north for the rest of the state.