Missouri River
Aiton's Encyclopedia (1910)
the chief tributary of the Mississippi. It is formed by the Jefferson, the Madison, and the Gallatin. They rise in the Yellowstone Park region. It executes a wide sweep through northern Montana; then turns southeastward through North and South Dakota . It separates Nebraska and Iowa, grazes the northwestern corner of Kansas, flows eastward through central Missouri into the Mississippi just above St. Louis. The length from the source of the Jefferson to the Mississippi is 3,000 miles. Including the lower Mississippi the total length is 4,200 miles, the longest water course in the world. It is navigable for flat-bottomed steamboats as far as Fort Buford, at the mouth of the Yellowstone. In high water boats reach Great Falls . The upper part of the river is a foaming mountain torrent. At one point it passes through the "Gate of the Rocky Mountains ," a narrow gorge about six miles long, with perpendicular walls 1,200 feet high. At Great Falls, Montana, the river descends in a series of leaps. The highest fall is eighty-seven feet. The total descent in sixteen miles is 350 feet. The principal tributaries of the Missouri are the Yellowstone, the Platte, and the Kansas. The total area drained is 500,000 square miles, not far from two-fifths of the entire Mississippi basin. The Missouri carries an immense amount of yellow silt, gaining for it the name of the "Big Muddy." This silt is constantly settling into mud banks, which are again scoured away most unexpectedly. The steamer channel shifts from week to week most unaccountably, rendering the river exasperatingly dangerous and difficult of navigation. The volume of water varies greatly. At one time the river is "on a tear." Its alluvial banks melt away in the flood like magic. In a few weeks the water has gone down and the river channel is a vast series of half exposed mud flats. By many the Missouri is held to be the main stream, but the comparatively constant volume of water in the Mississippi and the continuous direction of its valley are sound arguments for considering the Missouri a tributary stream. The chief cities on the Missouri are Great Falls and Fort Benton, Montana; Mandan and Bismarck in North Dakota ; Pierre and Yankton in South Dakota; Sioux City and Council Bluffs in Iowa; Omaha in Nebraska; Atchison, Leavenworth, and Kansas City , Kansas; Kansas City and Jefferson City, Missouri. See also articles on LEWIS AND CLARK EXPEDITION, MISSISSIPPI, and on the chief cities named.
What Has Changed in the Last Century
Aiton's 1910 description of a wild, silt-choked stream whose "steamer channel shifts from week to week" fits only parts of the river today. Under the Pick-Sloan plan authorized by the Flood Control Act of 1944, the Corps of Engineers built six great mainstem dams — Fort Peck, Garrison, Oahe, Big Bend, Fort Randall and Gavins Point — whose reservoirs drowned hundreds of miles of the Dakota and Montana channel, including large tracts of the Fort Berthold Reservation, while the lower river was straightened and revetted into a navigation channel to Sioux City. The falls at Great Falls that Aiton measured at eighty-seven feet were harnessed for hydroelectric power. Modern measurement also deflates the old boast of "the longest water course in the world": the Missouri is usually given as about 2,341 miles, and the Mississippi–Missouri system ranks fourth in the world rather than first.
Written for this edition, 2026.