Improved riverways and canals constituted the next advance in transportation method. So far as the latter were concerned, although the initial expense was great, the subsequent cost of movement as compared with turnpikes was, of course, low. Especially was this cheapness of movement notable in river traffic. Whereas it was said to cost one-third of the worth of goods to transport them by land from Philadelphia to Kentucky, the cost of carriage from Illinois down to New Orleans by water was reputed to equal less than five per cent, of their value. Hence the steamboat, invented in 1807 and introduced on the Ohio river in 1811, opened up vast possibilities for enlarged markets. But it was not until the generation of sufficient power to stem the rapid river currents about 1817 that our internal waterways became fully utilized.[2] From that period dates the rapid growth of Pittsburg, Cincinnati, and St. Louis. The real interest of the East in western trade dates from the close of the war of 1812. Even then, however, the natural outlet for the products of the strip of newly settled territory west of the Alleghanies, was still over the mountains to the Atlantic seaboard. Cotton culture in the South had not yet given rise to a large demand for food stuffs in the lower Mississippi valley. It was a long and wellnigh impossible way around by the Gulf of Mexico. Consequently the main attention of the people during the canal period between 1816 and 1840 was focussed upon direct means of communication between the coastal plain and the interior. A few minor artificial waterways, like the Middlesex canal from Boston to Lowell, completed about 1810, proved their entire feasibility from the point of view both of construction and profit. Even earlier than this the Dismal Swamp canal and one along the James river in Virginia had been projected and in part built. But the era of canal construction as such on a large scale cannot be said to begin until after the close of the war of 1812. The most important enterprise, of course, was the building of the Erie Canal to unite the headwaters of the Hudson river with the Great Lakes at Buffalo. This waterway, began in 1817, was completed in eight years and effected a revolution in internal trade. It was not only successful financially, repaying the entire construction in ten years, but it at once rendered New York the dominant seaport on the Atlantic. Philadelphia was at once relegated to second place. Agricultural products, formerly floated down the Susquehanna to Baltimore, now went directly over the Hudson river route. Branch canals all over New York state served as feeders; and flourishing towns sprang up along the way, especially at junction points. The cost of transportation per ton from Buffalo to New York, formerly $100, promptly dropped to less than one-fourth that sum. By wagon it was said to cost $32 per hundred miles for transport, whereas charges by canal fell to one dollar.