Hudson Bay drainage basin

The Hudson Bay drainage basin is the drainage basin in northern North America where surface water empties into Hudson Bay and adjoining waters. Spanning an area of about 3,861,400 square kilometres (1,490,900 sq mi), the basin is almost totally in Canada (spanning parts of the Prairies, central and northern Canada), with a small portion in the United States (in Montana, the Dakotas, and Minnesota). The watershed's headpoints are on the Continental Divide of the Americas, and the watershed's outlet at the Davis Strait is the Hudson Strait's mouth between Resolution Island in the Qikiqtaaluk Region and Cape Chidley on the Labrador Peninsula. On the Continental Divide the basin is bounded at Triple Divide Peak to the south, and Snow Dome to the north.

Usually considered part of the North Atlantic Ocean, Hudson Bay is sometimes said to be part of the Arctic Ocean, though its waters flow predominantly to the Atlantic.

The Hudson Bay drainage basin coincides almost completely with the former territory Rupert's Land, claimed by the Hudson's Bay Company in the 17th century, and an ideal area for the early fur trade in northern and central North America.