Upper Missouri River Breaks National Monument, National Monument in central Montana, United States.

The Upper Missouri River Breaks National Monument covers 377,000 acres of public land in north-central Montana, managed by the Bureau of Land Management. The Missouri River cuts through sandstone and shale, exposing layered cliffs along a roughly 240 km stretch. Pale grey-white rock formations with flat vertical faces and dark streaks rise from the water, with grass and low vegetation on lower ledges.

The monument was created by President Bill Clinton's proclamation on January 17, 2001, covering 377,000 acres of public land already managed by the Bureau of Land Management. The Lewis and Clark Expedition passed through in 1805, and its party made the first written and drawn records of the region. In 1877 the eastbound Nez Perce crossed the Missouri here; the Cow Island Skirmish was their last fight before surrendering at Bear Paw.

The Crow name for the Breaks is Xuáhcheesh Annáppiio, "Where the Crow warrior Skunk was killed." The confluence of the Judith and Missouri Rivers hosted peace councils between U.S. representatives and Native nations in 1846 and 1855. Tribes including the Blackfoot, Assiniboine, Gros Ventre, Crow, Plains Cree and Plains Ojibwa lived here once horses made the region habitable.

Access to the monument is primarily through U.S. Highway 87 from Fort Benton, though most areas require walking to explore properly. Visitors should wear sturdy footwear and bring plenty of water, as vehicle access is limited throughout the protected land.

The Breaks was the largest unroaded, undesignated federal tract in the contiguous 48 states before its 2001 protection. Two volcanic necks rise about 60 m above the surrounding prairie within the monument. The Crow name for the area, Xuáhcheesh Annáppiio, means "Where the Crow warrior Skunk was killed."