MISSOURI, a river in Louisiana, which falls into the Mississippi from the west, 195 miles above the mouth of the Ohio, and about 1160 miles from the Balize in the gulf of Mexico. Though the united rivers take the name of the Mississippi, the Missouri is much the largest branch. It was first explored by Captains Lewis and Clark in 1804, 1805, and 1806. It is navigable for boats to the great falls 2848 miles from its junction with the Mississippi, and even beyond
this almost to its source at the distance of 3096 miles from the Mississippi, making the total extent of navigation from the sea in one line above 4000 miles. Its width varies from 200 yards to a mile. Its velocity was found by the log to be about five miles an hour. It receives many large streams, the Yellowstone, Kansas, Platte, &c. chiefly on its south side; and it is computed that, including these branches, it affords an inland navigation of 15,000 miles. It carries down great quantities of earth, and has an annual swell like the Mississippi. Its sources in the Stony mountains are not far from those of the Columbia, which flows into the Pacific ocean. The distance to the South sea from the Mississippi by this route is 3555 miles.