MISSOURI, a river in the United States, the largest tributary of the Mississippi. Its headwaters are in southwestern Montana, and the Missouri River proper begins at the con •fluence of the Jefferson, Madison and rivers. The Madison has its source in Yellow stone Park, near the headwaters of Yellow stone River and the geysers in the western part of the park. The Gallatin also has its rise in the same park and not far from the source of the Yellowstone and Madison rivers. The Jef ferson rises farther west; its headwaters are near the source of the Snake River. The Missouri from the confluence of the three rivers flows north and east to the Bear Paw Moun tains, when it turns and flows south and east a distance of about 50 miles, when again the course changes toward the east, from the 108th meridian to about 107° 30' northeast, then east to North Dakota, which State it enters at 49° N. It has a very irregular course in the north western part of North Dakota, but it is gen erally southeast to South Dakota, which State it enters at 100° 20' W. It crosses the State of South Dakota, marking an irregular course, generally in a southeasterly direction to the boundary of Nebraska at 42° 45' N. From here it forms the boundary between South Dakota and Nebraska to Iowa at 42° 20', when it turns south and forms the boundary between Nebraska and Iowa, Nebraska and Missouri, and Kansas and Missouri to Kansas City, where it enters the State of Missouri, flows east by north to Bruns wick, then east by south, making two large curves, to the Mississippi which it enters 20 miles north of Saint Louis and three miles be low Alton, Ill. The length of the whole course from the source of the Madison River is about 2,915 miles, from the source of the Jefferson about 3,000 miles. From its source to the mouth of the Mississippi River is a total length of 4,200 miles, the longest continuous water-way in the world. There are some peculiar irregulari ties along its course, one in Montana, where the Musselshell River enters, is in the form of a ‘.(V," its opening toward the north, and the sides about 12 miles long. Along the course in each State there are long narrow loops, enclosing lands which are almost islands; across the State of Missouri the river forms three crescents, one pointing north and two pointing south.
The Missouri is noted for the great amount of suspended silt it always carries and which has given it the name •Big Muddy.° This silt is deposited in reefs which change the current, and frequently much damage results. In 1903 considerable damages were sustained by the washing away or grinding away of portions of Decatur, and Covington in Nebraska, Sioux City in Iowa and Yankton in South Dakota.
The river follows no known rules as to when or where it will deposit its burden of silt, change its current and begin to destroy a solid shore line. Dikes and stone walls have been constructed in many places. In the upper part of its course the Missouri passes through the *Gate of the Rocky Mountains,* a gorge about six miles long and having perpendicular walls about 1,200 feet in height. At Great Falls, Mont., there are a series of falls making vertical descent of 350 feet in 16 miles. The highest falls is 87 feet.
The chief tributaries are in Missouri, the Osage and Kansas; in Nebraska, the Platte and Nibrara; a large number of short streams in Iowa; the Big Sioux, White, James and Cheyenne, in South Dakota; the Little Missouri in North Dakota; and the Yellowstone and Milk in Montana. The extent of country drained by the Missouri and its tributaries is about 500,000 square miles or nearly two-fifths of the whole Mississippi Basin. The northern point of the basin of the Missouri extends al most to the Saskatchewan River. The Missouri is a swiftly flowing stream in its upper course, and for a distance of about 500 miles it presents scenes of almost unequaled grandeur. It forces its way through narrow gorges, foams over cataracts and winds around mountains. In the lower part of its course the waters move more slowly on its journeys across the vast plains. It is navigable in summer, during the flood period, to Great Falls, Mont., and in low water as far as Buford at the mouth of the Yellowstone River. The flat-bottomed steam boats are necessarily those used ' ir navigation on the Missouri.
The principal, cities on the river from the upper course to its mouth are Great Falls and Fort Benton in Montana; Bismarck, the capital of North Dakota; Pierre, the capital of South Dakota; Sioux City, Iowa; Omaha, Neb.; Atchison, Leavenworth and Kansas City, Kan.; Kansas City, Saint Joseph and Jefferson City, Mo. That portion of Iowa lying near the mouth of the Little Sioux and north for about 70 miles, between the Missouri and the Little Sioux, is below the level of the Missouri from 8 to 32 feet. The area of the tract below water level is about 840 square miles, and embraces some of the finest farms and most prosperous towns of the State.
The history of this river is connected with the history of the early explorers and mission aries and with the lives of the miners and settlers of the latter part of the 19th century. The possibilities in the unused water power of its upper course are enormous. The great prairies through which the river passes on its lower course contain the most productive lands in the United States.