the controlling influence of the Hudson Bay depression is seen for it receives the water from 1,400,000 square miles, almost half of the mainland of Canada. The Nelson River system drains 368,000 square miles, exclusive of a small area in the United States. From the head of the Bow River in the Rocky Mountains, its total length is 1,600 miles. Other important rivers entering Hudson Bay are the Churchill, 1,000 miles; Severn, 610 miles; Albany, 610 miles; Dubawnt, 580 miles; Eastmain, 510 miles; and the Moose 340 miles in length. The Koksoak River flowing into Ungava Bay is 660 miles long.
An area of over 900,000 'square miles drains to the Arctic Ocean, more than half of it by way of the Mackenzie. This river is the longest in Canada measuring 2,635 miles to the head of the Finlay, its most distant source. Its drainage basin contains some very large lakes including Great Bear, 12,000 square miles; Great Slave, 11,170 square miles; and Athabaska, 3,058 square miles in area. From Fort Smith on the Slave River, to Aklavik in the Mackenzie delta, a distance of nearly 1,300 miles is navigable for large river boats.
The Pacific receives the drainage from 400,000 square miles. The largest river is the Yukon which has a total length of 1,979 miles of which 714 miles are in Canada. Its drainage area in Canada is over 127,000 square miles, mostly in Yukon Territory. The Fraser River, with a total length of 850 miles, drains 80,000 square miles in the interior of British Columbia. The Columbia has a total length of 1,150 miles of which 459 are in Canada, draining an area of over 40,000 square miles.
The St. Lawrence is the greatest river draining to the Atlantic coast of North America. Its total length is 1,900 miles and it drains an area of 359,000 square miles in Ontario and Quebec as well as a considerable area in the United States. Its basin contains the five Great Lakes: Superior, 31,820 square miles; Michigan, 22,400 square miles; Huron, 23,010 square miles; Erie, 9,940 square miles and Ontario, 7,540 square miles. The lakes and rivers of the St. Lawrence system form a remarkable inland waterway for nearly 2,000 miles into the heart of the continent. Niagara Falls on the Niagara River between Lake Erie and Lake Ontario has a drop of 160 feet and is one of the most spectacular waterfalls in the world. It is also a great source of hydro-electric power. The Hamilton River drains a great plateau in Labrador, the Grand Falls on this river are over 300 feet high.
During the early history of the country its rivers and lakes were very important as routes of travel. The development of land transportation has greatly reduced this function in many cases. As the country has developed many rivers have been harnessed for power. This is particularly true of the rugged areas of the Canadian Shield and Cordilleran region.