 Many U.S. national parks , such as Glacier National Park , Rocky Mountain National Park , Yellowstone National Park and Badlands National Park are in the watershed . Parts of other rivers in the basin are set aside for preservation and recreational use – notably the Niobrara National Scenic River , which is a 76 @-@ mile ( 122 km ) protected stretch of the Niobrara River , one of the Missouri 's longest tributaries . The Missouri flows through or past many National Historic Landmarks , which include Three Forks of the Missouri , Fort Benton , Montana , Big Hidatsa Village Site , Fort Atkinson , Nebraska and Arrow Rock Historic District . 
 Many U.S. national parks , such as Glacier National Park , Rocky Mountain National Park , Yellowstone National Park and Badlands National Park are in the watershed . Parts of other rivers in the basin are set aside for preservation and recreational use – notably the Niobrara National Scenic River , which <a href='drop_aux' title='1'><mark>is</mark></a>a 76 @-@ mile ( 122 km ) protected stretch of the Niobrara River , one of the Missouri <a href='null_genetive' title='2'><mark>'s</mark></a>longest tributaries . The Missouri <a href='uninflect' title='3'><mark>flows</mark></a> through or past many National Historic Landmarks , which include Three Forks of the Missouri , Fort Benton , Montana , Big Hidatsa Village Site , Fort Atkinson , Nebraska and Arrow Rock Historic District . 
Many U.S. national parks , such as Glacier National Park , Rocky Mountain National Park , Yellowstone National Park and Badlands National Park are in the watershed . Parts of other rivers in da basin are set aside for preservation and recreational use – notably tdaNiobrara National Scenic River , which a 76 @-@ mile ( 122 km ) protected stretch of the Niobrara River , one of thdaissouri  longest tributaries . Thedassouri flow thru or past many National Historic Landmarks , which include Three Forks of the dasouri , Fort Benton , Montana , bigg Hidatsa Village Site , Fort Atkinson , Nebraska and Arrow Rock Historic District .