 <unk> from Great Falls , Montana , about 149 miles ( 240 km ) of the river course through a rugged series of canyons and badlands known as the Missouri Breaks . This part of the river , designated a U.S. National Wild and Scenic River in 1976 , flows within the Upper Missouri Breaks National Monument , a 375 @,@ 000 @-@ acre ( 1 @,@ 520 km2 ) preserve comprising steep cliffs , deep <unk> , arid plains , badlands , archaeological sites , and whitewater rapids on the Missouri itself . The preserve includes a wide variety of plant and animal life ; recreational activities include boating , rafting , hiking and wildlife observation . 
