In some respects conditions in the United States compare with those of Continental Europe, for they suggest alike powerful streams, artificial canals constructed on (as a rule) flat or comparatively flat surfaces, and the possibilities of traffic in large quantities for transport over long distances before they can reach a seaport. In other respects the comparison is less with Continental than with British conditions, inasmuch as, for the last half century at least, the American railways have been free to compete with the waterways, and fair play has been given to the exercise of economic forces, with the result that, in the United States as in the United Kingdom, the railways have fully established their position as the factors in inland transport best suited to the varied requirements of trade and commerce of to-day, while the rivers and canals (I do not here deal with the Great Lakes, which represent an entirely different proposition) have played a rôle of steadily diminishing importance. The earliest canal built in the United States was that known as the Erie Canal. It was first projected in 1768, with the idea of establishing a through route by water between Lake Erie and the River Hudson at Albany, whence the boats or barges employed would be able to reach the port of New York. The Act for its construction was not passed, however, by the Provincial Legislature of the State of New York until 1817. The canal itself was opened for traffic in 1825. It had a total length from Cleveland to Albany of 364 miles, included therein being some notable engineering work in the way of aqueducts, etc. At the date in question there were four North Atlantic seaports, namely, Boston, New York, Philadelphia, and Baltimore, all of about equal importance. Boston, however, had appeared likely to take the lead, by reason both of her comparatively dense population and of her substantial development of manufactures. Philadelphia was also then somewhat in advance of New York in trade and population. The effect of the Erie Canal, however, was to concentrate all the advantages, for the time being, on New York. Thanks to the canal, New York secured the domestic trade of a widespread territory in the middle west, while her rivals could not possess themselves of like facilities, because of the impracticability of constructing canals to cross the ranges of mountains separating them from the valley of the Mississippi and the basin of the Great Lakes--ranges broken only by the Hudson and the Mohawk valleys, of which the constructors of the Erie Canal had already taken advantage. So New York, with its splendid harbour, made great progress alike in trade, wealth, and population, completely outdistancing her rivals, and becoming, as a State, "the Empire State," and, as a city, "the financial and commercial centre of the Western Hemisphere."