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Encyclopaedia Brittanica

Fig. 1  The Missouri river.


THE TRUE SOURCE OF THE MISSOURI RIVER

Victor M. Ponce


200314


1.  SOURCE OF A RIVER

The source of a large river system, for example, the Missouri river, is often taken as the location of the uppermost spring in the farthest tributary. Under this optic, the source of the Missouri river would be Brower's Spring (Fig. 2), located in the headwaters of Hell Roaring Creek, in southwestern Montana, near the border with Idaho (Fig. 3). The spring is named after Jacob V. Brower, who in 1896 declared it to be the source of the Missouri river in his book The Missouri river and its utmost source. However, the name Brower's Spring is not listed as an official name on the Geographic Names Information System maintained by the U.S. Geological Survey.

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Aualliso (Wikimedia Commons)

Fig. 2  Brower's Spring, in the headwaters of Hell Roating Creek,
in southwestern Montana.


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Panoramio (Google Earth ®)

Fig. 3  Hell Roaring Creek, in southwestern Montana, the most upstream tributary of the Missouri river.


2.  MISSOURI RIVER BASIN

The Missouri River is the longest river in North America. With its source in the Rocky Mountains of western Montana, the Missouri flows first north, then east and south for 3,767 km (2,341 miles) before joining the Mississippi River north of St. Louis, Missouri. The river drains a sparsely populated, semiarid watershed of 1,370,000 square kilometers (529,200 square miles), which comprises parts of ten U.S. states and two Canadian provinces. Although nominally considered a tributary of the Mississippi, the Missouri River is much longer and carries a comparable volume of water. The combined Missouri-Mississippi forms the world's fourth longest river system in the world.

The longest tributary of the Missouri river begins a short distance upstream of Brower's Spring, on the southeastern slopes of Mount Jefferson, in the Centennial Mountains of the Bitterroot Range (click on top of Fig. 4 to see red arrow in the large display). From there it flows first as Hell Roaring Creek, then west into Red Rock Creek; then it swings northeast to become the Beaverhead River; and finally it joins the Big Hole to form the Jefferson river. The latter joins the Madison river to become the Missouri River at Missouri Headwaters State Park near Three Forks, Montana (see actual location in the large display of Fig. 4).

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U.S. Geological Survey

Fig. 4  Missouri river basin, indicating the location of Brower's Spring, in southwestern Montana,
and the location of Three Forks, Montana, where the Missouri river is named.


3.  SOURCE OF THE MISSOURI RIVER

The true source of the Missouri river is in the Rocky Mountains, on the U.S. Continental Divide, at 44° 33' 27.2" N and 111° 28' 9.55" W, at an elevation of 2,864 m (9,396 ft) (Fig. 5). By comparison, Brower's Spring is at 44° 33' 0.74" N and 111° 28' 25.2" W, at an elevation of 2,684 m (8,806 ft) (Fig. 6). Table 6 shows the geographical data for the two points.


Table 1  Geographical data of true source and Brower's Spring.
Point Elevation
(m)
Latitude Longitude
True source 2,864 44° 33' 27.2" N 111° 28' 9.55" W
Brower's Spring 2,684 44° 33' 0.74" N 111° 28' 25.2" W


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Google Earth ®

Fig. 5  Panoramic view of the true geographical source of the Missouri river.


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Google Earth ®

Fig. 6  Panoramic view of the location of Brower's Spring.

The distance between the two points may be calculated using the online calculator online_geodistance_two. The result shows that the distance is 886.64 m (2,908.9 ft) (Fig. 7).

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Visualab

Fig. 7  Distance between Brower's Spring and the true geographical source of the Missouri river.


4.  LEWIS AND CLARK EXPEDITION

The Lewis and Clark Expedition, which took place between May 1804 and September 1806, was the first official American expedition to cross the western portion of the United States. It began in Pittsburgh, Pennsylvania, making its way westward to eventually reach the Pacific Ocean. The expedition was composed of a volunteer group of U.S. Army soldiers under the command of Captain Meriwether Lewis and his close associate Second Lieutenant William Clark.

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Abridged from ushistory.org

Fig. 8  Route of the Lewis and Clark expedition (red outbound; blue inbound).

The river portion of the expedition departed from Camp Dubois, Illinois, near the present-day Wood river, on May 14, 1804, ascended the Missouri river and came close to its source in Montana, proceeding instead to the Pacific Ocean. On August 12, 1805, they crossed the U.S. Continental Divide at Lemhi Pass and reached the Salmon river. Finding the latter too risky to navigate, they decided instead to portage onto the neighboring watershed (Fig. 9), descending the Clearwater river to reach the Snake river and, eventually, the mouth of the Columbia on November 20, 1805 (Figs. 10 and 11).

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U.S. Geological Survey

Fig. 9  Lewis and Clark on the Lower Columbia river.


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Charles Marion Russell (Humanities Texas)

Fig. 10  Lewis and Clark on the Lower Columbia river.


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Frederic Remington (fineartamerica.com)

Fig. 11  Lewis and Clark at the mouth of the Columbia river.


200317 14:35 (PDT)
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