(6) Hinterland.—Even if an inland waterway were ideal in other respects, it would not carry much commerce unless it had a well-popu lated hinterland able to supply raw materials, food, or manufactured goods in exchange for products brought from afar. Compare the Danube and the Yukon. The Danube flows through some of the most densely populated and progressive parts of the world. Hence it carries thousands of boats of all sizes from small ocean steamers and large canal barges down to rowboats. So far as natural advantages for navigation are concerned, the Yukon is little inferior to the Danube except for the long frozen period from October to April. Neverthe less, it does not carry one boat for a hundred on the Danube, for its hinterland contains only a few miners who do not consume much, and do not furnish any articles of export in quantities large enough to supply cargoes.
(7) Direction.—The direction is the one feature of inland water ways which man cannot control. He can deepen and broaden a river, or increase the navigable length and overcome falls and rapids by building canals and locks. He can straighten windings, control the current, overcome the effects of seasonal changes, and populate the hinterland, but he cannot change the general direction in which a river flows. Yet this condition is the most important in determining the ,rialue of an inland waterway. The Rhine is a relatively small river, i3ut because it flows toward the place where England nears the con tinent, and where are located Rotterdam, Antwerp, and London, it supports nr incredibly active commerce. The 'MacKenzie and the Ob are han the Rhine, hut in a year they carry no more com ae Rhine does in a day, for they flow toward the frozen north .i toward the places where trade and manufacturing are active.
The Good Inland Waterway of the St. Lawrence and the Great Lakes.—Let us now take a few of the world's great systems of inland waterways and see how they stand in respect to the seven require ments mentioned above. The St. Lawrence River and the Great Lakes form one of the world's finest systems. They furnish a broad, deVrarai relatively penetrating about ffi the interior. however, LathIrCini Sainte Marie rapids and the falls of Niagara, but these have been partly overcome by canals and locks so tharships drawing 14 feet can go from the seato Another and more serious difficulty is that although seasonal changes have no great effect upon the depth of the water, t ey cause the St. Lawrence realLa s closed by eior throb Monthnuring the winter. Such difficulties, however, are more than compensated by the wonderful hinterland which includes the great grain regions of the central plains, the unexcelled iron deposits near Larninimntor, the immense coal mines of Pennsyvarrithe rich fa):alamls-of New York ansoti&rCanada. Moreover, throughout the Great Lakes
region the direction of this great waterwayis_almost ideal, for it con nects regions of three ,great types producing food, raw , and manufact g.ed oods. Down the St. Lawrence is so far as relations with Europe are concerned. It would be far better, however, if the river flowed to New York and the great markets on the Atlantic coast instead of to the barren coasts of Labra dor and Quebec. This has made it advisable to dig the New York State Barge Canal, 362 miles long, which extends from Buffalo to Albany, where it connects with the Hudson River. This canal, however, is only 12 feet deep, so that neither lake nor ocean steamers can enter it, and trans-shipment is necessary at each end. For this reason it carries only one-fiftieth as many tons of freight as the Sault Sainte Marie at the outlet of Lake Superior. In 1920 the tonnage car ried by the canals of New York State was only about a fourth as great as in 1880, but it is hoped that this will now rapidly increase.
The Excellent Waterway of the Rhine and the German Canals.— The system of inland waterways of which the Rhine is the main artery owes its importance to its hinterland and its direction. Because the Rhine flows through an extremely populous and progressive region and toward the center of the world's activities, the Germans and Dutch have found it worth while to deepen and broaden it; to increase its navigable length by canalizing certain parts; to straighten out the windings; to provide cables to pull ships up through the strong est currents; and to make provision for the regulation of e;:, ds. To take further advantage of this excellent waterway, the Germans have built many canals to connect it with the Weser, Elbe, and other rivers farther east. The canals greatly enlarge the hinterland, and enable traffic to move east and west rather than in a more northerly direction along the line of the main rivers. Thus goods from the Vistula River can now be carried to Holland by inland waterways without breaking bulk. The Rhine and the German canals well illustrate the tendency of commerce to aim straight at the most thickly settled industrial regions. A detour to the Baltic Sea, where the surrounding population is much less dense than around the North Sea, is much like a detour down the St. Lawrence to Newfoundland.