The first attempt to guard the lower part of the valley against the river floods was in 1717, when the French governor, De In Tour, ordered embankments for the protection of New Orleans. In 1728 the French planters of Louisiana were protecting each his own water-front, and soon after combined for joint work by neighborhoods and parishes. In 1828 the state of Louisiana began to take rigorous action for the more complete pro tection of its delta lands. In 1836 and 1838 several of the great side channels by which inundations had come were closed at the expense of the counties, and the question of the closing of all the overflow channels, so as to confine the stream to one bed in all stages of water, was the subject of much excited difference of opinion. The closure party prevailed, and one by one the side outlets of the Mississippi were cut off by levees, so that by 1844 every old river lake inlet for 600 m. up the w. bank bad been effectually closed. The results were even more satisfactory than had been expected, so that Ike levee system was entered upon with increased spirit by the states bordering the river, and the aid of the general government was invoked to unify the work. Congress, in -1850, ordered thorough topographical and hydrog,raphie surveys of the whole Mississippi delta, under the direction of capt. A.. A. Humphreys and lieut. H. L. Abbott, who began work immediately; but the report was not submitted until Aug., 1861. While the U. S. government were thus obtaining complete data for the completion of the whole work, not only with reference to the reclamation of the vast and fertile deltas of the river, but with reference. to the thorough-improvement of its navigation from the gulf to its upper waters, the: states most interested in the levees cOntinuedavark upon them till checked by the operations of the rebellion in 1852-04. By the report of Humphreys and Abbott, in 1861, it appears that substantial levees had been constructed on the e. side up to the n. line of the state of Mississippi, including one of great magnitude across the Yazoo pass—the largest of all the outlets closed; and that above on the e. side tame of great magnitude were required. On the w. side the levees had been completed to the mouth of the Arkansas, and were partially completed, including the line 25 in. long opening into the St. Francis valley.
This was the condition of the lower Mississippi at the beginning of the rebellion. Louisiana alone had expended up to that time $18,000,000 on the levees of the main river; $5 000,000 more on its great side outlets, the Atchafalaya, Plaquemine, and La Fourche; and $1,000,000 on the shore of the Red river. The state of Arkansas had spent $1,000,000; Mississippi, on her water-front of 444 m., $14,500,000; and the state of Missouri, on her front of 140 in., $1,640,000. The total expenditure by individuals, parishes, and states up to that time, on about 2,000 m. of the river shore, is estimated by C. G. Fershey, of New Orleans, at upwards of $41,000,000, without counting the cost of its maintenance. The report of Humphreys and Abbott, in 1801, recommended confin ing the river to a single channel and making the levees higher at all points, and rela tively as follows: at the month of the Ohio, 3 ft. above the highest flood ever known (which was then that of 185S); 7 ft. above from Osceola to Helena; 10 ft. above from Helena to island No. 71; thence down to Napoleon 8 ft.; thence to Lake Providence to be increased to 11 ft.; thence to the month of the and Red River Landing to be reduced to about 6 ft.; and below to be reduced gradually to 3 ft.; and they estimated the cost of carrying out this recommendation at $17,000,000. The tendency of all streams to build up the level of their bottoms by liars formed at their mouths was met by a recommendation to construct a jetty system at the main mouth of the Mississippi, by which its depth should be increased and maintained.
The subject of levee construction was again taken up by the U. S. government by an act of June 22, 1874, authorizing president Grant to appoint a board of commissioners to make a full report on the best system for the permanent reclamation of the delta basin of the Mississippi. Maj.gen. G. K. Warren and gen. Humphreys were put at the head
of the commission, and reported, Jan. 22, 1875, substantially the recommendation of the preceding report, carried further up the great tributaries of the lower Mississippi; that the general government should make and enforce the laws necessary to execute and pro tect the work; and that the work should be divided "into six natural drainage districts, viz.: 1. The St. Francis bottom-lands, comprising the w. bank of the river from Cape Girardeau to Helena; 2. the White river bottom-lands, lying between Helena and the month of the Arkansas; 3. the Tensas bottom lands, extending from the Arkansas to the ltcd river; 4. the Yazoo bottom-lands, lying between the bluffs below Memphis and Vicksburg on the e. bank; 5. Louisiana below Red river on the w. bank; and 6. Louisi ana below Baton Rouge on the e. bank. In each of these districts the commission recommended the appointment of is single controlling engineer, with full power in his district, subject to the control of a board composed of the chiefs of each department. The cost of the entire work recommended by this commission by districts was as follows: The annual cost of maintenance is estimated at $2,000,000. The length of levees estimated on is 1775 miles.
The commissioners state the amount of land reclaimed and to be reclaimed by this system "at least 2,500,000 acres of sugar land, 7,000,000 acres of the best cotl 011 land in the world, and not less than 1,000,000 acres of corn land of unsurpassed and inex haustible fertility." Other authorities place the area that will be reclaimed as high as 23,000,000 acres of good land. This probably includes the swamps that may be subse quently reclaimed.
The three main mouths or passes of the river to the gulf diverge where the river has treble its mean width, that is about 7,500 ft., with a mean depth of about 26 feet. It is through the South pass that the recent great work of the government under capt. Fades has been done to deepen and confirm the main channel, and prevent the rise in the level of the bottom of the river. The outer edge of the bar formed at the month of the South pass since 1838 was found to have pushed into the gulf about 300 ft. a year. The depth of the gulf at the foot of the slope_formed by the deposits of the river is from 300 to 500 ft., the course of the nrain or South pasg being direct tornydots•deOper water's.
The report front which these facts are drawn is published under the title of the Total expenditures for four years ending June 1, 1879, $4,710,208. • The deltas of the lower Mississippi are everywhere threaded with interlacing bayous and navigable channels, placing every cultivable acre of their lands near to steamboat navigation, one-tenth of the land being estimated as taken up by such water surfaces or channels. Below lat. 31° 30' the sugar-cane is grown on the delta only. Cotton is grown nearly the entire length of it, but most advantageously north of lat. 31°. Corn and sweet potatoes are grown in every part of its whole area, and in the northern parts potatoes and time cereals do well.
The timber growing in the delta region of the Mississippi is mostly sycamore, cypress, and oak—the former margining the streams, the cypress occupying the swamps, and the oaks the lands not liable to frequent inundation, the live oak being principally found Ivithin a law hundred miles of the gulf.
The climate of the Mississippi valley ranges from semi•arctic to semi-tropical. At the fails of St. Anthony, and above, spirit thermometers must be employed to register the extreme low temperature in winter, which often touches 40° Fahr., and yet the extreme of summer heat is but a few degrees less at St. Paul than at New Orleans, 97° to 104°. The range between the extremes is about 65° more at the source than at the mouth of the river. The annual mean temperature at New Orleans is 69'; at Cairo, 45°.
For the history of the discovery and first settlements of Mississippi, see DE SOTO;