Laurentian Divide

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Continental divides in North America. The Laurentian Divide is in green.

The Laurentian Divide or Northern Divide is a continental divide dividing the direction of water flow in eastern and southern Canada and the northern Midwestern United States. Water north of the height of land flows to the Arctic Ocean by rivers to Hudson Bay or directly to the Arctic. Water south of the divide makes its way to the Atlantic Ocean by a variety of streams, including the Great Lakes and Saint Lawrence River to the east, and the Mississippi River to the Gulf of Mexico to the south.

On the north and east, the divide starts at Cape Chidley on the Labrador Sea in Canada where that sea, part of the Atlantic Ocean, meets Hudson Strait which connects to Hudson Bay in the Arctic Ocean. The divide passes through eastern Canada, dips into the United States, and re-enters Canada before terminating in the Rocky Mountains in the western United States.

In Canada, the height of land forms the border between Quebec and Labrador (part of Newfoundland and Labrador). It turns west to cross southern Quebec and Ontario. Waters east and south of the divide flow into the Labrador Sea, the Gulf of St. Lawrence, or the Saint Lawrence River and the Great Lakes which are drained by that river. On the border between the U.S. and Canada, in the Boundary Waters Canoe Area Wilderness, this divide is known as the Height of Land Portage.

Marker sign for the Divide along Highway 101 in Ontario.

The divide crosses into the United States in northeast Minnesota, where it forms a three-way divide at the Hill of Three Waters where the watersheds of the St. Lawrence and the Mississippi River systems meet with the Hudson Bay basin. It crosses to the extreme northeast corner of South Dakota and passes through North Dakota to that state's northwestern corner. The U.S. sections of the divide separate the watersheds of the Rainy River and Red River of the North from the basins of the Mississippi and Missouri Rivers. The divide formed the northern boundary of the United States' Louisiana Purchase.

The divide crosses the southern parts of the Canadian provinces of Saskatchewan and Alberta before dropping back into the United States where it meets the Great Divide at Triple Divide Peak in Glacier National Park in Montana. The Northern Divide there becomes part of the Great Divide, running north through western Canada and northern Alaska through that state's Seward Peninsula to the sea.