The Missouri is the longest river in North America, flowing for 2341 miles (3767 km) and closely followed by the Mississippi River at 2320 miles (3730 km). Originating from the Rocky Mountains range in West America, it flows through east and south before its confluence with the Mississippi to the North of St. Louis.

Together the two rivers form the world’s fourth longest river system which drains a rain scarred region of nearly half a million square miles. The Missouri alone passes through 10 states in United States and two Canadian provinces.

Missouri – the Longest River in North America

The Missouri was long considered as a route from the Atlantic to the Pacific; before a military exploration expedition in 1804-06 led by Capt. Meriwether Lewis and Second Lieutenant William Clark proved it to be a myth.

Origin and Course

The Missouri River forms upon the confluence of three streams originating from, the Rocky Mountains range in the West American states of Montana and Wyoming. Two of the springs Jefferson and Madison converge at Missouri Headwaters State Park, Montana; marking the official beginning of the Missouri River. The Missouri is joined by the Gallatin River nearly a mile downstream from its origin.

Just within hundred miles from its origin, the Missouri is impounded by Canyon Ferry Dam in Helena, Montana to form the third largest reservoirs of Montana covering a shoreline of 122 km. It then passes through the Craig city, from where it turns northeast passing through the town of Great Falls. Here the river encounters five consecutive falls within a span of 10 miles (16 km); known as the ‘Great Falls of the Missouri River’. The total drop in the river from its first fall to the fifth is around 187 meters.

After the Great Falls, the river turns east passing through dry badlands known as The Missouri Breaks’ ; where it receives another east flowing river ‘Marias’ on its left bank.

Around 140 miles downstream of the Great Falls and just a few miles after the confluence with Musselshell river, the Missouri is once again impounded by the Fort Peck Dam near the city of Glasgow; forming a huge reservoir with a 216 km shoreline near the city of Glasgow.

Immediately after passing through the Fort Peck Dam the Missouri is joined by Milk River on its left bank. From there it flows through the plains of Montana, passing through the wolf point city; before receiving the Poplar River on its left bank.

It moves on towards east into North Dakota before it is joined by one of its greatest tributaries by volume- ‘The Yellowstone River’; on its right bank. Passing through North Dakota it encounters Garrison Dam forming Lake Sakakawea having 2120 km shoreline.

 

Passing through the Garrison Dam, Missouri turns south and receives rivers- Knife, Heart and Cannonball before passing into South Dakota. It continues south before coming across the Oahe Dam forming Lake Oahe with a shoreline of 372 km.

The river starts turning towards southeast passing through Pierre- the state capital of South Dakota. Flowing past Pierre, the river encounters the Big Bend where it makes almost a complete circular loop, traversing 25 miles before returning to the neck; which is hardly a mile broad. It then flows on towards south to get impounded by the Big Bend Dam just seven miles downstream of the Big Bend, forming Lake Sharpe having a shoreline of 320 km.

Just before it proceeds to form the boundary between South Dakota and Nebraska, it encounters another Dam, Fort Randall Dam, forming ‘Lake Francis Case’ with a shoreline of 870 km. The river moves on further to be impounded by Gavins Point Dam at Yankton, South Dakota forming Lewis and Clarke Lake with a shoreline of 40 kilometers.

The river passes through Sioux City in Iowa state and Omaha in the state of Nebraska before it meets its largest tributary ‘Platte River’ coming from the west on its right bank; few miles downstream of Omaha. From there it proceeds to form the Nebraska-Missouri border and Kansas Missouri border. From the city of Kansas the river turns east and continues into Missouri State.

After receiving the Grand River on its left bank the Missouri turns south east flowing through the cities of Columbia and Jefferson. From Jefferson it turns east to meet the Mississippi river coming from south at St. Louis.

Drainage Area

The total drainage area of the Missouri River is huge and comprises of nearly one sixth of the total area of the United States at 13,71,000 square kilometers. It extends from the semi arid plains of Rocky Mountains in west to the huge Mississippi River basin in east.  From north to south it ranges from the border of Arkansas River basin to western Canada.

 

Missouri is twice as long as the Mississippi from the point of confluence and provides nearly 45% of its total flow. The catchment area of Missouri has been home to millions living on agriculture and livestock. Nearly 28000 sq km of land is used for farming of wheat, barley, flax and oats.

The drainage area of Missouri has 1,17,000 sq km of forested area and 34,000 sq km of urban area.

Discharge

The Missouri has an average discharge of 2748 cubic meter/second, maximum discharge of 21238 cubic meter/second and minimum discharge of 17 cubic meter/second. The discharge of the River reaches to its maximum during the months of April and June due to the snow melt in its drainage area.

The largest ever recorded discharge of the Missouri was over 21000 cubic meter/second on 31st July 1993, resulting in great floods from May to October 1993.

The lowest ever discharge of the Missouri (17 cubic meters/second) was recorded on 23rd December 1963 and was caused due to the formation of ice dam.

Dams on the Missouri River

There are presently fifteen dams on the Missouri with a total generation potential of 2787 MW. The dams on the Missouri, their reservoirs and the capacities are listed below.

  • Big Bend Dam in South Dakota forming Lake Sharpe; with a total installed capacity of 493 MW.
  • Black Eagle Dam in Montana forming Long Pool; has a total installed capacity of 21 MW.
  • Canyon Ferry Dam in Montana forming Canyon Ferry Lake and having a capacity of 50 MW.
  • Cochrane Dam with a total installed capacity of 64 MW.
  • Dam Fort Peck in Montana forming fort peck Lake and a total capacity of 185 MW.
  • Fort Randall Dam in South Dakota forming Lake Francis Case and having a capacity of 320 MW.
  • Garrison Dam in North Dakota forming Lake Sakakawea; has a capacity of 515 MW.
  • Gavins Point Dam in South Dakota forming Lewis and Clark Lake; has a total capacity of 132 MW.
  • Hauser Dam in Montana forming Hauser Lake; has an installed capacity of 19 MW.
  • Holter Dam in Montana forming Holter Lake; has an installed capacity of 48 MW.
  • Morony Dam in Montana with a total capacity of 48 MW.
  • Oahe Dam in South Dakota forming Lake Oahe; with a total installed capacity of 786 MW.
  • Rainbow Dam in Montana with a capacity of 36 MW.
  • Ryan Dam in Montana with a capacity of 60 MW.
  • Toston Dam, Montana with a total capacity of 10 MW.

Tourism

The tourists’ influx to the various reservoirs of the Missouri and the 6000 km long Lewis and Clarke trial has been significantly increased in past few decades. The recreational activities in the Missouri are estimated to contribute nearly to 100 million dollars to economy.

Missouri’s watershed has many national parks – Rocky Mountain National Park, Badlands National Park, Yellow Stone National Park and Glacier National Park. Missouri also flows through many places of historical significance- Big Hidatsa Village Site, North Dakota; Arrow Rock, Missouri; Fort Atkinson, Nebraska and Fort Benton, Montana.

FAQs About Longest River in North America

Q1) Which is the longest river in North America?

Ans- Missouri River is the longest river in North America.

Q2) How long is the Missouri River?

Ans- The Missouri River is 2341 miles (3767 km) long.

Q3) Through how many states does the Missouri pass during its flow?

Ans- During its flow the Missouri passes through 10 states in the United States and two Canadian Provinces.

Q4) Missouri was considered as a route between which two oceans?

Ans– In the past Missouri was considered as a route from Atlantic Ocean to the Pacific Ocean.

Q5) When was the path of flow of Missouri explored?

Ans– The Missouri was explored by a military exploration expedition in 1804-06 led by Capt. Meriwether Lewis and Second Lieutenant William Clark.

Q6) Where did the Missouri originates?

Ans– The Missouri originates in the Rocky Mountain Range of West American states of Montana and Wyoming.

Q7) Name the springs which confluence to form the Missouri River?

Ans- Three springs, Jefferson, Madison and Gelatin confluence to form the Missouri River.

Q8) What marks the official beginning of the Missouri River?

Ans- The confluence of Jefferson and Madison at Missouri Head Waters State Park, Montana marks the official beginning of the Missouri River.

Q9) Where did the Gallatin River joins Missouri?

Ans– The Gallatin River joins the Missouri a few miles downstream from the confluence of Jefferson and Madison springs.

Q10) What is the name for the confluence of three streams forming the Missouri?

Ans- The confluence is known as Three Forks.

Q11) Which is the first dam on the Missouri?

Ans- Canyon Ferry Dam in Helena, Montana is the first dam on the Missouri.

Q12) How many falls constitute the Great Falls?

Ans- Great Falls is a name given to consecutive five falls encountered by the Missouri within a span of 16 kilometers.

Q13) What is the total drop of the River; while passing through the Great Falls?

Ans- The Missouri drops for nearly 187 meters while passing through the Great Falls.

Q14) Where did the Missouri receives Marias River?

Ans- The Missouri receives another east flowing river ‘Marias’ on its left bank while passing through the badlands known as Missouri breaks.

Q15) In which city is the Fort Peck Dam on Missouri located?

Ans– The Fort Peck Dam on the Missouri is located in the city of Glasgow.

Q16) Where did the Yellowstone River joins Missouri?

Ans– The Yellowstone River joins Missouri on right bank in the state North Dakota.

Q17) When did the Missouri encounters Big Bend?

Ans– The Missouri encounters the Big Bend after flowing through Pierre; the capital of South Dakota.

Q18) What is the length of the loop formed by Missouri at the Big Bend?

Ans– The length of the loop formed by the Missouri at the Big Bend is 25 miles.

Q19) What is the width of the loop neck?

Ans– The loop neck of the Great Bend is almost a mile broad.

Q20) Which North American state does the Missouri forms the official boundary of?

Ans– The Missouri River forms the boundary between South Dakota-Nebraska, Nebraska-Iowa, Kansas-Missouri.

Q21) Which is the largest tributary of the Missouri and where does it meets?

Ans– The largest tributary of the Missouri is ‘Platte River’ coming from the west which joins it on right bank; few miles downstream of Omaha.

Q22) When did the Missouri River meets the Mississippi River?

Ans– The Missouri River meets the Mississippi River at St. Louis.

Q23) How much is the total drainage area of the Missouri River?

Ans– The total drainage area of the Missouri River is 13,71,000 square kilometers.

Q24) How much area of the catchment is used for agriculture?

Ans– Nearly 28000 sq km of land is used for farming of wheat, barley, flax and oats.

Q25) What is the average discharge of the Missouri River?

Ans– The average discharge of the Missouri River is 2478 cubic meter/second.

Q26) How much is the recorded maximum discharge of the Missouri River?

Ans– The maximum recorded discharge of the Missouri River is 21238 cubic meter/second.

Q27) How much is the recorded minimum discharge of the Missouri River?

Ans– The minimum recorded discharge of the Missouri River is 17 cubic meter /second.

Q28) When did the Great Floods of Missouri occurred?

Ans– The Great Floods of the Missouri had occurred in 1993.

Q29) How many dams are built on the Missouri River?

Ans– Fifteen dams are built on the Missouri River.

Q30) How much is the total installed capacity of the dams?

Ans– The total installed capacity of the dams on the Missouri River is 2787 MW.