The Erie Canal was constructed over an eight-year period beginning in 1817. It was part of a national effort to stimulate commerce that included the construction of the National Road and numerous lighthouses as well as protective tariffs. Once the canal was open, it became cheaper, in some cases 90% cheaper, to ship goods, especially agricultural produce, from upstate New York and the Old Northwest, which were now linked to the harbor at New York City by water. This stimulated settlement of these regions and urban growth in the small towns in the region. It also stimulated the development of further canals in the Old Northwest, which joined an even greater expanse of land to the network of waterways connected by the Erie Canal. These networks extended to most of the Northwest with the development and expansion of railroads. Perhaps most important, the development of the canal solidified New York City's position as the most important trade center in the country.