Missouri River

Missouri River

The Missouri is one of the largest rivers in North America, flowing through several U.S. states, including Montana, Nevada, and Missouri. The Missouri River is the longest river in North America, about 2,341 miles (3,767 km) long.
The Missouri River is a major tributary of the Mississippi River and together with it forms the largest water system in North America.


When U.S. President Thomas Jefferson (1743-1826) petitioned Congress on January 18, 1803 for $2,500 (no small sum at the time!) to expand foreign trade, he actually conceived of an expedition that resulted in one of the most important milestones in the history of land exploration in North America.

Jefferson attached such importance to exploring the Missouri River basin and the possibility of a water route to the Pacific that he appointed his own secretary, Captain Meriwether Lewis (1774-1809), to lead the expedition. Lewis chose as his mate Lieutenant William Clark (1770-1838).

The lands Lewis and Clark had purchased from France in 1803, which Lewis and Clark were to explore, had previously been explored exclusively by “enthusiasts” – fur traders and trapper hunters – without even official maps. Although, of course, Lewis and Clark could use the data collected in the 18th century by French trappers.

The president personally instructed the expedition: “The object of your mission is to investigate the Missouri River and its principal tributaries, its course and connection with the waters of the Pacific, and to ascertain whether the shortest and most profitable route across the Continent might be taken by the Columbia, Oregon, Colorado, or any other river for trade. In addition, maps had to be made, all reliable data on minerals had to be plotted, and as much information about Indian tribes as possible had to be gathered.

Lewis and Clark devised their plan to sail up the Missouri River, cross the Rocky Mountains (while also determining the geographic coordinates of their peaks and canyons), and then use the Columbia River (after studying its navigability) to reach the Pacific Ocean.

The voyage up the Missouri began in mid-May 1804. The expedition’s diaries recorded the abundance of game (beavers, deer, bison) and encounters with groups of Indians.

By early December, having covered 2,500 kilometers, the expedition established Fort Mandan (named after a friendly Indian tribe) and remained there over the winter.

In April 1805, the expedition moved on – now in a completely unknown territory, without plans and maps. Instead of large riverboats, the travelers built small canoes because large boats were unsuitable for navigation in the upper Missouri. The Indians helped Lewis and Clark a great deal by describing navigational conditions on the Missouri and by providing a guide who knew the local roads.

In 1805 the expedition succeeded in crossing the Rocky Mountains and reaching the Pacific Ocean. They discovered Great Falls and the source of the Missouri, the Tri-Forks, “the Trident,” the confluence of three rivers, which they named. The westernmost and largest river was named for President Jefferson, the middle one for Madison, and the eastern one for Gallatin, after the President’s supporters.

The expedition was especially fortunate in that among the Indians who accompanied it was the wife of a Trapper-French Indian, Sacagawea, who knew the place well. She showed the passes through the Rocky Mountain passes. On November 15, 1805, Lewis and Clark and their companions reached the shore of the Pacific Ocean. In the spring of 1806, the expedition set out on its return journey. They were already considered dead in their homeland, and when Lewis and Clark returned to St. Louis on September 23, 1806, a grand welcome awaited them.

The results of the Lewis and Clark expedition are hard to overestimate: real maps and scientific descriptions of new lands appeared, and the way to the west of the continent was discovered. The expedition’s diaries were published in 1814, providing detailed accounts of the difficulties of traveling up the Missouri River and of the natural features of the land. Two maps based on the expedition gave detailed accounts of the opportunities to develop new territories.

Lewis and Clark were followed by new explorers and numerous tracts of fur traders and later settlers in Kansas and Nebraska. Up the river came more and more seekers of a better life, whole caravans of settlers. The river helped the strong survive and spared no expense to the weak.

And for decades St. Louis and Kansas City had served as the “Gateway of the West,” the most frequent point of departure for pioneers.

The Longest River in the United States

Today, the Missouri is the longest river in the United States and North America, and there are virtually no unexplored or undeveloped areas along its banks. At the headwaters of the three rivers that make up the Missouri, Yellowstone National Park was established in 1872. Near the rapids of Great Falls, where the water drops 187 meters over a stretch of 16 km, is Canyon Ferry Reservoir. A network of large reservoirs (more than 100) is created all over the Missouri, and the river banks in particularly dangerous areas are fortified to avoid flooding.

By the way, serious flooding on the Missouri is not uncommon. For example, in the spring of 2009, North Dakota was declared a disaster zone and ice jams had to be blown up on the Missouri to prevent the city of Bismarck from flooding. There were 100 major floods in the Missouri Basin between 1940 and 1950. The last one was in 1952. Since then, the floodplain downstream (from the mouth of the James River) has been dammed, and water disasters are a thing of the past.

The water in the Missouri is still muddy, muddy brown in color, thanks to the rocks that have washed out. So the name Missouri, from Native American for “dirty river,” is still relevant. Running through Montana, North Dakota, and South Dakota, the Missouri forms the water border of Iowa, Kansas, and Nebraska.

In its upper reaches, the Missouri retains its mountain river character; in its middle reaches, crossing the Missouri Plateau, the river becomes a chain of long reservoirs. And in its lower reaches, the Missouri still tends to change channel, forcing man to keep a close eye on the river’s intentions. The Missouri is fed by snow in its upper reaches; in its middle and lower reaches it is mostly rain fed.

Another unpleasant consequence of river basin development, the Missouri has indeed become one of the dirtiest rivers in the world, its banks contaminated with dioxins, the river carrying runoff from industries and communities along its banks. Its lower reaches have elevated levels of radioactive elements and heavy metals.

General Information

  • The Missouri River is the largest tributary of the Mississippi.
  • Headwaters: Southeast Montana, confluence of the Jefferson, Madison, and Gallatin Rivers.
  • Estuary: the Mississippi River.
  • Main tributaries: right – Arrow Creek Yellowstone, Little Missouri, Knife, Cheyenne, Bad River, Platte, Osage, Kansas; left – Milk, Big Sioux, Jams.
  • Country through which the river flows: United States.
  • U.S. states through which the Missouri River flows: Montana North Dakota, South Dakota, Iowa, Kansas, Nebraska.
  • The largest cities in the basin are: St. Louis. Kansas City.
  • Main river ports: Kansas City. St. Louis, Sioux City, Omaha.
  • Major basin lakes: Canyon Ferry, Sharpe, Lewis & Clark, Fort Peck, Sacagawea, Oahe, Francis Keys, Lake Te Ozarks.
  • Basin area: 1,370,000 km2, of which 10,000 km2 are in Canada.
  • River length: 4,740 m.
  • Water flow rate: 2,250 m3/sec.
  • The “highest” point of the basin: Granite Peak, 3,901 m.

Climate and weather

  • Throughout the river, the climate is generally continental-arid to moderately continental.
  • Average temperature in January: about 0 ºC. July: +25 ºC.
  • Average annual precipitation: About 1,000 mm (Missouri).


  • Hydroelectric power – hydroelectric power plants of Fort Peck, Harrison, Oahe, Big Bend, Fort Randall, Gavins Point.
  • Shipping – large riverboats sail up to Sioux City.
  • Irrigation of agricultural land.
  • Tourism.


  • Yellowstone National Park.
  • Fort Union Trading Post National Historical Museum.
  • Little Bighorn National Monument.
  • Fort Clark.
  • Fort Rye.
  • Fort Bennett.
  • Badlands National Park.
  • Mark Twain National Wildlife Refuge.
  • Jefferson National Expansion Memorial (St. Louis).

Fun Facts

  • The unofficial name for the city of St. Louis is “Gateway to the West.” From here, in the second half of the 19th century, hundreds of thousands of settlers set out to explore the still wilderness. The harsh climate, clashes with bands of militant Indians and between settlers meant that only the most hardy survived and succeeded, and many died on the way to new lands. To commemorate this, the Gateway Arch appeared in St. Louis, listed in the Guinness Book of World Records as the largest monument in the United States, the height and width of the arch – 192 meters.
  • The city of Kansas City is a unique agglomeration. In fact it is two cities of the same name, and territorially belonging even to different states. The city on the right bank of the Missouri River is in the state of Kansas, and the city on the left bank is in the state of Missouri. The “left bank” Kansas City has three times as many residents as the “right bank” city. But the two cities have long since merged into one, and the maps simply say Kansas City.
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