The U.S. Supreme Court case Missouri v. Nebraska; Nebraska v. Missouri in 1904 was a dispute over the boundary line between the two states, specifically regarding an area of land around the Missouri River which had changed course since the original border demarcation. The controversy arose due to changes in river channels and accretion formations that led to ambiguity about state jurisdiction over certain lands along their shared border. Both states claimed ownership of this territory based on different interpretations of past treaties and laws defining their borders, leading them to bring their cases before the Supreme Court for resolution under its original jurisdiction authority for disputes between states. The court ruled that when a river constituting a boundary between states changes its bed by avulsion (a rapid change), it does not affect or alter state boundaries even if there is significant alteration in geography as long as identifiable parts of old channel remains intact - meaning that despite geographical shifts, legal boundaries remain unchanged unless explicitly redefined by law or agreement.

In the dissenting opinion for Missouri v. Nebraska; Nebraska v. Missouri, 1904, it was argued that the Supreme Court did not have jurisdiction over this case as it involved a dispute between two states about water rights and boundaries along the Missouri River. The dissenting justices believed that such disputes should be resolved through negotiation or arbitration rather than litigation in federal court. They also disagreed with the majority's interpretation of an 1851 treaty with Native American tribes which had established certain territorial boundaries along the river. According to them, this treaty did not give either state exclusive control over any part of the river but merely recognized existing tribal rights and territories at that time.