“ The Ohio is commercially the most important tributary, and in flood time most of the commerce on the Lower Mississippi consists of coal and other heavy freight received from the mouth of this river. Its navigation at low water has also been improved by dredging, rock excavation and contraction works. In its upper reaches a channel 9 ft. in depth had been obtained before 1909 by the construction of a number of locks with collapsible dams which are thrown down by a flood. ”

“ But at the beginning of the 20th century the prospects of communication with the western coast of North America and South America, and with the Orient by way of an isthmian canal, the inadequate means of transportation afforded by the railways, the efficiency of competing waterways in regulating freight rates, and the consideration of the magnificent system of inland waterways which the Mississippi and its tributaries would afford when fully developed, have created the strong demand for river improvement. ”

“ 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. ”

“ The development of the Mississippi Valley must have been slow until the railways came had it not been for the timely application of the power of steam to overcome the strong current of the Lower Mississippi. Even without the steamboat, however, the Mississippi was indispensable to the early settlers, and the delay of the United States in securing for them its free navigation resulted in threats of separation from the Union. ”

“ In 1817 the commerce from New Orleans to the Falls of the Ohio, at Louisville, was carried in barges and keel-boats having a capacity of 60 to 80 tons each, and 3 to 4 months were required to make a trip. In 1820 steamboats were making the same trip in 15 to 20 days, by 1838 in 6 days or less; and in 1834 there were 230 steamboats, having an aggregate tonnage of 39,000 tons, engaged in trade on the Mississippi. Large numbers of flat boats, especially from the Ohio and its tributaries, continued to carry produce down stream ”

“ The grades of the levees are usually 3 ft. above the highest water, and have to be raised from year to year as greater confinement of water gives greater flood heights. When this system is completed there will probably be hundreds of miles of levee with heights exceeding 14 ft. In 1899, after about $28,000,000 had been spent on levees by the United States and by the local authorities, the commission submitted an estimate for additional work on levees, amounting to 124,000,000 cub. yds. and costing $22,000,000. The effect of the levees has been to increase flood heights. ”

“ 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 5 1/5 ft. above the level of the Gulf, where the mean tidal oscillation is about 1 1/5 ft. ”