The Great Lakes

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

None of the five Great Lakes formed the way a lake usually does, by a river filling a natural basin. All five are the direct product of continental glaciation: over the last roughly two and a half million years, repeated ice ages sent glaciers a mile or more thick grinding south across the region, gouging out and deepening basins that had already been weakened by older river valleys and softer rock, then damming the resulting depressions with glacial debris as the ice retreated for the last time, roughly fourteen thousand years ago. That single shared origin explains why the five lakes, despite ranging enormously in size and depth, from Lake Superior largest and deepest to the much shallower Lake Erie, sit in a connected chain rather than as unrelated bodies of water, each basin the product of the same ice sheet working the same regional geology at a slightly different point in its retreat. The result is water in a scale almost impossible to picture: the five lakes together hold roughly a fifth of the world's surface fresh water, more than enough, if spread evenly, to cover the entire continental United States to a depth of about ten feet.

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

Four of the five Great Lakes, Superior, Huron, Erie and Ontario, straddle the international border between the United States and Canada, and the fifth, Lake Michigan, lies entirely within the United States but drains into the same connected system, so the lakes function as one shared hydrological and economic system regardless of the line drawn through the middle of four of them. That shared geography built one of the busiest inland shipping corridors on Earth: the St. Lawrence Seaway, completed in 1959 through a joint US-Canadian engineering project, opened a navigable route from the lakes all the way to the Atlantic, letting ocean-going vessels reach ports as far inland as Duluth, Minnesota, over two thousand kilometers from the sea. Cities on both shores, Chicago, Detroit, Cleveland and Toronto among them, grew into industrial centers precisely because the lakes gave them cheap water transport to move raw materials and finished goods in every direction at once. Governing a shared resource that size across an international border has needed its own machinery too, formalized in the 1909 Boundary Waters Treaty and the joint bodies it created, among the oldest continuously operating instances of two countries managing one body of water together.