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See T. A. Owen, “A Biography of Mississippi,” in the Annual Report of the American Historical Association, 1899, i. 633-828 (Washington, 1900); “Report of the Mississippi Historical Commission” in the Publications of the Mississippi Historical Society, v. 52-310 (Oxford, Miss., 1902). J. F. H. Claiborne’s Mississippi as a Province, Territory and State (Jackson, 1880), gives the best account of the period before the Civil War. R. Lowry and W. H. McCardle, History of Mississippi (New York, 1893), is useful for local history. Of most value for the history are the writings of P. J. Hamilton, J. W. Garner and F. L. Riley. Hamilton’s Colonial Mobile (Boston and New York, 1898), and the Colonization of the South (Philadelphia, 1904) are standard authorities for the French and English periods (1699–1781). Garner’s Reconstruction in Mississippi (New York, 1902) is judicial, scholarly and readable. Most of Riley’s work is in the Publications of the Mississippi Historical Society (Oxford, 1898 seq.), which he edited; see his Spanish Policy in Mississippi after the Treaty of San Lorenzo, i. 50-66; Location of the Boundaries of Mississippi, iii. 167-184; and Transition from Spanish to American Rule in Mississippi, iii. 261-311. There is much material in the Encyclopaedia of Mississippi History (2 vols., Madison, Wisconsin, 1907), edited by Dunbar Rowland. There is a state Department of Archives and History.

 MISSISSIPPI RIVER, the central artery of the river system which drains the greater part of the United States of America lying between the Appalachian Mountains on the east and the Rocky Mountains on the west. It rises in the basin of Itasca Lake, in northern Minnesota, and flows mostly in a southerly direction to the Gulf of Mexico. In the region of its headwaters are numerous lakes which were formed by glacial action, but the river itself was old before the glacial period, as is shown by the crumbling rocks on the edges of the broad and driftless valley through which it flows along the S.E. border of Minnesota and the S.W. border of Wisconsin, in contrast with the precipitous bluffs of hard rock on the edges of a valley that is narrow and steep-sided farther down where the river was turned from its ancient course by the glacier. So long as the outlet of the Great Lakes through the St Lawrence Valley was blocked by the icy mass, they were much larger than now and discharged through the Wabash, Illinois and other rivers into the Mississippi. Below the glaciated region, that is from southern Illinois to the Gulf, the river had carved before the close of the glacial period a flood-plain varying in width from 5 to 80 m., but this has been filled to a depth of 100 ft. or more with alluvium, and in the post-glacial period an inner valley has been formed within the outer one. The total length of the river proper from the source near Lake Itasca to its mouth in the Gulf of Mexico is 2553 m.; but the true source of the river is at the fountain-head of the Missouri, in the Rocky Mountains, on the S.W. border of Montana, 8000 ft. above the sea, and from this source there is a continuous stream to the Gulf which is 4221 m. long—the longest in the world. The Mississippi and its tributaries have more than 15,000 m. of navigable waterways and drain an area of approximately 1,250,000 sq. m. The system extends through the heart of the continent and affords a direct line of communication between temperate and tropical regions. Certain physical and hydrographic features, however, make the regulation and

control of the Mississippi below the influx of the Missouri an exceedingly difficult problem.

The Upper Mississippi, that is the Mississippi from its source to the mouth of the Missouri, drains 173,000 sq. m., over which the annual rainfall averages 34·7 in., and its discharge per second into the Lower Mississippi varies from 25,000 cub. ft. to 550,000 cub. ft. The Missouri drains 528,000 sq. m., over which the annual rainfall averages 19·6 in., and its discharge per second into the Mississippi varies from 25,000 cub. ft. to 600,000 cub. ft. The Ohio drains 214,000 sq. m., over which the annual rainfall averages 43 in., and its discharge per second varies from 35,000 cub. ft. to 1,200,000 cub. ft. The Arkansas drains 161,000 sq. m., over which the annual rainfall averages 28·3 in., and its discharge per second varies from 4000 cub. ft. to 250,000 cub. ft. The Red drains 97,000 sq. m., over which the annual rainfall averages 38·3 in., and its discharge per second varies from 3500 cub. ft. to 180,000 cub. ft. These and a few smaller tributaries produce a river which winds its way from Cape Girardeau, Missouri, to the passes through a flood plain averaging about 40 m. in width and having a general southern slope of 8 in. to the mile. The general lateral slope towards the foothills is about 6 in. in 5000 ft., but the normal fall in the first mile is about 7 ft. Thus the river sweeps onward with great velocity, eroding its banks in the bends and rebuilding them on the points, now forming islands by its deposits, and now removing them. Chief among the changes is the formation of cut-offs. Two eroding bends gradually approach each other until the water forces a passage across the narrow neck. As the channel distance between these bends may be many miles, a cascade perhaps 5 or 6 ft. in height is formed, and the torrent rushes through with a roar audible for miles. The checking of the current at the upper and lower mouths of the abandoned channel soon obstructs them by deposit, and forms in a few years one of the crescent lakes which are so marked a feature on the maps. At the mouth of the Red river 316 m. above the passes, the water surface at the lowest stage is only ft. above the level of the Gulf, where the mean tidal oscillation is about ft. The river channel in this section is therefore a fresh-water lake. At the flood stage the surface rises 50 ft. at the mouth of Red river, but of course retains its level at the Gulf, thus giving the head necessary to force forward the increased volume of discharge. Above the mouth of the Red river the case is essentially different. The width increases and the depth decreases. Hence the general slope in long distances is here nearly the same at all stages. The effect of these different physical conditions appears in the comparative volumes which pass through the channel. At New Orleans the maximum discharge hardly reaches 1,200,000 cub. ft. per second, and a rising river at high stages carries only about 100,000 cub. ft. per second more than when falling at the same absolute level; but just below the mouth of the Ohio the maximum flood volume reaches 1,400,000 cub. ft. per second, and at some stages a rising river may carry one-third more water than when falling at the same absolute level. The river is usually lowest in October. It rises rapidly until checked by the freezing of the northern tributaries. It begins to rise again in February, as a consequence of the storms from the Gulf which traverse the basin of the Ohio, and attains its highest point about the 1st of April, it then falls a few feet, but the rains in the Upper Mississippi basin cause it to rise again and high water is maintained until some time in June by the late spring and early summer rains in the Missouri basin. As a rule the river is above mid-stage from January to August inclusive, and below that level for the remainder of the year.

Engineering Works.—Below Cape Girardeau there are at least 29,790 sq. m. of rich bottom lands which require protection from floods, and this has been accomplished to a great extent by the erection of levees. The first levee was begun in 1717, when the engineer, Le Blond de La Tour (d. about 1725) erected one a mile long to protect the infant city of New Orleans from overflow. Progress at first was slow. In 1770 the settlements extended only 30 m. above and 20 m. below New Orleans; but in 1828 the levees, although quite insufficient in dimensions, had become continuous nearly to the mouth of the Red river. In 1850 a great impulse was given to systematic embankment by the United States government, which turned over to the several states all unsold swamps and overflowed lands within their limits, to provide a fund for reclaiming the districts liable to inundation. The action resulting from this caused alarm in Louisiana. The aid of the government was invoked, and Congress immediately ordered the necessary investigations and surveys. This work was placed in charge of Captain (later General) Andrew A. Humphreys (1810–1883), and an elaborate report covering the results of ten years of investigation was published, just after the outbreak of the Civil War in 1861. In this report it was demonstrated that the great bottom lands above the Red river, before the construction of their levees did