MISSISSIPPI, a river of North America, and one of the largest in the world. It rises in some lakes about the latitude of 48°, and runs in a direction nearly south to the gulf of Mexico. Its course, including windings, is about 2500 miles in length, and it is navigable from the sea to the falls of St Anthony in latitude 44° 50'. Its width is from 800 yards to a mile and a half. Its depth above New Orleans has been found to be 150 feet; but there is only from 12 to 17 feet water on the bars at its mouth. Its current is from three to four miles an hour, but varies with the rise and fall of the waters. In low water a boat will float down at the rate of 45 or 50 miles a day, and in high water at 90 or 100. Towards the mouth the current is much less rapid than farther up. The usual progress of a boat up the river is about 15 miles a day; but the steam-boats, of which there are now great numbers.
Mississippi, Missouri. bers on this river, go against the stream at the rate of 60 miles a-day. This river has an annual swell, which begins in November, and increases till May, from which period it again diminishes till October. The greatest rise from the mouth of the Ohio to Natchez is about 50 feet; but at New Orleans is only about 12 feet. During this annual flood a part of the waters pass over the western banks, inundate the country to a considerable extent, and never return into the bed of the river, but either form marshes, or pass off to the sea by different channels. In the lower part of its course the banks are higher than the surrounding country; and, besides the waters that overflow during the floods, a part always escapes by lateral branches, which intersect the country towards its mouth in various directions, and form a delta about 200 miles long by 100 broad. This tract, inclosed within the branches of the river, is, for the greater part, a morass nearly on a level with high water. It has evidently been formed by alluvial matter brought down and deposited by the river, and it is observed to be continually enlarging.
The Mississippi receives in its course a great many very large rivers, the Illinois and Ohio on the east; the Missouri, Arkansas, Red River, &c. on the west. Including all its branches, Mr Bradbury computes that it waters a country eleven times as large as Great Britain and Ireland.