Five States Bordering the Missouri River: The Upper Basin Quartet Plus Missouri

The Missouri River—North America's longest river at 2,341 miles—forms or crosses boundaries for five U.S. states along its course from Montana's Rockies to its Mississippi confluence at St. Louis.

The Five States (Upstream to Downstream)

1. Montana – Headwaters at Three Forks (Jefferson, Madison, Gallatin); flows north through Great Falls, Fort Peck Lake (134 mi reservoir), to North Dakota border
2. North Dakota – Enters at Williston; Lake Sakakawea (Garrison Dam, 178 mi); Bismarck; exits at South Dakota border
3. South Dakota – Lake Oahe (Oahe Dam, 231 mi); Pierre (capital on river); Lake Sharpe (Big Bend Dam); exits at Nebraska border
4. Nebraska – Forms NE-SD border (Lewis & Clark Lake, Gavins Point Dam); Omaha/Council Bluffs metro; exits at Missouri border
5. Missouri – Enters at NW corner; Kansas City; flows east across state; joins Mississippi at St. Louis (Gateway Arch)

States Often Confused as Bordering

• Kansas – Only touches Missouri River at extreme NE corner (Doniphan County, ~1 mile); not a significant border state
• Iowa – Borders Mississippi River; Missouri River forms IA-NE border only briefly at Sioux City (technically IA-SD-NE tripoint)
• Wyoming, Colorado – Tributary headwaters only (Yellowstone, Platte)

River Character by State

Management Framework

• Missouri River Basin Compact – Interstate water allocation
• USACE Master Manual – 8 purposes: flood control, navigation, hydropower, irrigation, water supply, water quality, recreation, fish/wildlife
• Tribal nations – 28 tribes with reserved rights; Fort Berthold, Standing Rock, Crow Creek, Lower Brule, others
• Endangered species – Pallid sturgeon, least tern, piping plover drive flow management

Historical Significance

Lewis & Clark (1804-06), steamboat era (1819-1880s), transcontinental railroad crossing (1869), Pick-Sloan Plan (1944) dams. The river shaped the Louisiana Purchase territory's exploration, settlement, and economic geography.