Canal this trend. Yet in other countries canals grew in size as construction techniques improved. During the 19th century in the US, the length of canals grew from to over 4,000, with a complex network making the Great Lakes navigable, in conjunction with Canada, although some canals were later drained and used as railroad rights-of-way. In the United States, navigable canals reached into isolated areas and brought them in touch with the world beyond. By 1825 the Erie Canal, long with 36 locks, opened up a connection from the populated Northeast to the Great Lakes. Settlers flooded into regions serviced by
Great Lakes region area urban planners call the Great Lakes Megalopolis, which has an estimated 59 million people. Chicago is emerging as the third megacity in the United States, after the New York City and Los Angeles metropolitan areas, with a metro population approaching ten million. Cities along the Great Lakes have access to the Atlantic Ocean through the St. Lawrence Seaway, making them international ports. The Palaeozoic strata, are but parts of a great area of similar strata hundreds of feet in thickness. These strata decline gently southward from the great upland of the Laurentian Highlands of eastern Canada. The visible upland