The second waterway is the network of routes within the Great Lakes. The opening of the Erie Canal in 1825 completed an all-water shipping route, more direct than the Mississippi, to New York and the seaport of New York City. In 1848, The Illinois and Michigan Canal breached the continental divide spanning the Chicago Portage and linking the waters of the Great Lakes with those of the Mississippi Valley and the Gulf of Mexico. Lakeport and river cities grew up to handle these new shipping routes. During the Industrial Revolution, the lakes became a conduit for iron ore from the Mesabi Range of Minnesota to steel mills in the Mid-Atlantic States. The Saint Lawrence Seaway, completed in 1959, opened the Midwest to the Atlantic Ocean.