The great compactness of the territory and the lack of deep inlets and inland seas partly compensates for the vast network of inland waterways formed by the Great Lakes, the Mississippi and its tributaries and the rivers that flow into the Atlantic and completed by canals artificial. Less fortunate is the western section, where the navigability of the rivers on the Pacific side is limited to short stretches. However, even the large belt of highlands does not constitute a continuous barrier and does not oppose insurmountable obstacles to the opening of artificial roads, since the tributaries of the Missouri and Mississippi to the East., and those of the Columbia and Colorado to the West, mark with their valleys, numerous natural paths, separated by passes that are not excessively high or difficult.
In the early days of colonization, the roadways had very little extension and communications with the interior took place only through paths traveled on foot or on horseback: however, from the colonial centers of the east coast some roads advanced to the foot of the eastern reliefs. Only from the beginning of the nineteenth century did they begin to provide for the opening at public expense of roads leading to the central plains, such as the one begun in 1806 from Cumberland, Maryland, to Illinois, and the one from Philadelphia to Pittsburg; but the cost of road transport from Pennsylvania to Philadelphia, over a distance of thirty miles, exceeded the sea freight from England to Philadelphia. As a result, the exploitation of inland waterways began early, especially in the Atlantic area, where estuaries and rivers made it possible to cross the maritime plain to the line of the cascades. In O. degli Allegani, Ohio was of great importance and became the gateway to the West, through which the pioneers received their tools from the eastern centers and shipped their products to Pittsburg, Cincinnati, Louisville. The introduction of steamships, the first of which crossed the Ohio in 1811, made it possible to connect Pittsburg with New Orleans by river, while the construction of the Erie-Canal, connecting the Hudson Valley to the Great Lakes, facilitated communications to the high Mississippi and determined the conditions of development of New York.
Later the construction of the railways had to give the penetration inwards a truly colossal impetus. In 1840 the number of railways open to traffic was already considerable, but they were short lines that departed from the ports of the Atlantic coast and were not connected to each other. Starting from 1850, however, railway constructions developed with increasing rhythm, so much so that by 1870 they had already largely supplanted communications by water, and the railway network in 1860, with its 49,000 km., Exceeded the entire network. European. Completely neglected, however, was the construction of ordinary roads, which only in the century. XX was imposed by the rise of motoring.
Inland waterways. – The network of canals and navigable rivers measures over 40,000 km. The waterways, thanks to the extraordinarily favorable conditions of the rivers and the ease of connecting the various valleys with canals, preceded ordinary roads in time; but their importance has been decreasing with the progress of railway communications, so much so that the 7200 km. of canals built to connect navigable rivers and to connect the Atlantic coast with the Great Lakes and the Ohio Valley, over a third have remained unused: only the canals of the NE. they are still in full working order. Among the rivers that flow from the Allegani to the Atlantic, the Hudson is first which, thanks to the tide, can be ascended up to Albany by ships of a thousand tons: the Hudson is joined to the South. Lorenzo by the channel that crosses Lake Champlain, and Lake Erie and Ontario with the Mohawak and Erie canals. The latter leaves from Buffalo, on Lake Erie, and, with a distance of 584 km., Reaches the Hudson in Waterford, overcoming a vertical drop of 174 m. Built in 1825, it was repeatedly enlarged and doubled with the State Barge Canal, which overcomes the difference in height with 35 basins. Lake Erie is then joined with the Huron by the Detroit channel, and with Lake Superior by the two channels (Canadian and American) of Santa Maria. These works, together with the great Canadian channel dug to go around the obstacle of the Niagara waterfall, connect the Great Lakes with the Atlantic, both through the St. Lawrence and through the Hudson.
The heavy traffic of these interlacal canals always has an enormous volume and through them the products of the inland area, such as the wheat of the upper Mississippi, the iron and copper of the Lake Superior, the coal of Pennsylvania, the agricultural commodities and the machines from Duluth, Chicago, Detroit and Buffalo have free passage to the Atlantic.
The Mississippi, which is navigable from St. Paul’s and is accessible to large steamers downstream from Saint Louis, is connected to the Great Lakes by the Illinois Canal, and Ohio, with the channels that join it to the Great Lakes and Philadelphia, it always has massive traffic. In 1930 the canals of the state of New York had a movement of goods of 3,270,000 tons, of which 2,761,000 tons. they passed through the water lines of the Erie-Division; the St Marys Falls Canal in the same year carried 66,118,000 tons. of goods.
The ports of the Great Lakes overall reached a traffic of 106 million tons arriving and 110 million departing: Buffalo received 11 million and shipped 2.3 million; Chicago, respectively, 10.2 and 1.4 million; Duluth 10.2 and 31.2 million; Cleveland 8.7 and 1.9 million; Milwaukee 5.5 and 1.7 million tons of freight.
However, these waterway systems are impaired by summer droughts and winter freezes: the Hudson itself is barred by ice for three months of the year. And since the Mississippi flows down to the Gulf of Mexico, while the trading posts are located on the shore of the Atlantic, a great many goods, especially those of value, are sent to eastern ports and markets by rail.