The junction of the Red introduces us to still another phenomenon. That great river for merly discharged its main waters to the Gulf through the Atchafalaya (tBayou,)) roughly par allel with the •Mississippi; but that and the Mississippi both sent their surplus waters through an amazing network of lesser bayous, which still penetrate southern Louisiana with thousands of miles of navigable channels. The head of the Atchafalaya silted up and became choked with logs and rubbish, and the Red opened a channel into the Mississippi; later in the 19th century the government dredged out the head of the bayou to make a navigable channel; it rapidly widened to a great river, became again the main channel of the Red and threatened to ruin a great district of fertile plantations, so that works had to be undertaken to prevent its enlargement. As we approach the place where the Mississippi plain merges in the great coastal plain of the Atlantic, the surface grows lower and the soil spongier; and the river (which above the Mississippi is about a mile wide, thence to the Red half a mile to a mile, with occasional reaches of a mile and a half, and below the Red nartows to a width of about 3,000 feet, which it retains with curious persistence) widens to about a mile and a half and enters the Gulf — through the Delta, a quaking, impassable, finally half liquid salt marsh land in process of making— by three great arms or "passes;' of which two ramify still further. These are known as the Southwest Pass, the South Pass (with two arms near the Gulf) and an eastern arm soon dividing into North Pass and Pass l'Outre.
It should be said, however, that these allu vial bottoms do not quite monopolize the space from the Ohio to the Gulf. Here and there on the east bank there are spots where high solid ground, old capes and peninsulas of the antique ocean, come down to the river side; as at Columbus, Ky., Randolph and Memphis, Tenn., Vicksburg, Grand Gulf and Natchez, Miss., and Baton Rouge, La. With one exception, each of these spots has been utilized as a considerable road for the commerce of the interior to the great waterway.
Improvements of the River.— These are broadly divisible into two classes: those de signed to improve navigation and those de signed to prevent overflows. From 4 March 1789 to 30 June 1886, a period of 97 years, in the improvement of the Mississippi and its 44 navigable tributaries, the Federal government expended a total sum in round numbers of about $57,000,000. The control of the waters of the Mississippi so as to make the navigation of the river safe and so as to make the imme diately surrounding country fit for agriculture has been an economic problem of more than merely local interest. The problem is national historically, for to the control of the Mississippi as much as to any other one thing the histori cal growth of the country is due. It is even more strikingly true that the problem is of national significance from the commercial point of view, simply because this vast river drains the richest territory in the world, 70 per cent of the area of the United States. Among the older methods of control was that of narrow ing the channel to deepen the available water. This operation involved closing off side chan nels around islands, etc.— stopping up the heads, diking off small bays and inlets, strengthening caving banks and obstructing the side current by solid spur dikes, set obliquely out into the stream nearly to the channel line.
After the entrance of the Missouri, the mass of sediment furnishes a new and effective weapon. Between here and Cairo hurdles of piles and brush are laid along the banks, jetty fashion; the sediment packs into the brush and speedily becomes solid, and the results in cre ating new banks to narrow the channel have been most gratifying, besides reclaiming large tracts of overflowed bottom lands. Caving banks are protected by mattresses; the depth of water being slight, they are made lighter than in the lower river. Below Cairo the work is of the same nature, but more difficultsfrom the volume of water and the alluvial lands easily crumbling. Here the channel is nar rowed, where it exceeds about 3,500 feet, by mattresses from 800 to 2,000 feet long and 200 to 300 feet wide, weighted down with rubble stone. But the immense weight of water, which may be from 60 to 100 feet deep at flood, has forced their continual increase in weight and strength of construction. The brush and small saplings have been replaced by fascines (solid rods tightly withed together), the binding poles by strong wire; the cost per foot of bank pro tection trebling in 25 years, from about $10 to $30. For closing off side channels and water courses, rows of piles are driven in, 8 or 10 feet apart and the rows 20, and the upper row interwoven with brush. Caving banks are graded down to a slope and faced with mat tresses; of late, however, rubble stone has been used with better success. On the lower river, where stone has to be brought from long dis tances, concrete has been experimented with Another system is that of levees. For merly, under the slave system, each planter along the rivers liable to overflow had rude dikes erected for himself ; the importance of the work to neighborhoods led to common town action, then to county and State action. These levee systems, of course, were broken through in floods, but the water rose only to. its natural height in the channel and soon, subsided; and to furnish absolute against overflow would cost not only an enor mous sum but would exceed a hundredfold the capital value of the districts imperiled. When in 1879 Congress appointed the Missis sippi River Commission, it forbade them to consider the protection of lands from overflow as part of their work. Nevertheless a majority of the commission believed that the levee sys tem could be used efficiently to improve naviga tion, and estimated that $11,443,000 below Cairo would furnish a complete protection for the banks and double the depth of permanent river channel, by the natural scour of the water as with jetties. The level of the river has risen with the levees over six feet and is esti mated to ultimately reach 11 when the levee system has made a smooth solid bank all the way, with no place for overspill. These levees' are from 8 to 14 feet high, with a width on top of eight feet and a side slope of they project three feet above high water, but need to be raised every few years as the river rises. They have to be placed near the banks to protect riverside plantations and avoid the slope away from the river; and very large amounts of them have to be replaced yearly from cave-ins.