Students to learn about ecology of Saginaw Bay aboard Appledore IV
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5 | To the ocean and beyond
The Great Lakes and St. Lawrence River are part of a vast system linking North America's heartland with ports and markets throughout the world. The world's longest deep-draft inland waterway, the system extends from Duluth, Minn., on Lake Superior, to the Gulf of St. Lawrence on the Atlantic Ocean, a distance of more than 2,340 miles. This shortcut to the continent's interior was made possible with the construction of a ship canal and lock system opened in 1855 at Sault Ste. Marie, Mich., the development of the Welland Canal since 1829, and the completion of the St. Lawrence Seaway in 1959.
The Soo Locks
Detailed Map: The Great Lakes - St. Lawrence River system
The U.S. Congress passed an act in 1852 granting 750,000 acres of public land to the state of Michigan as compensation to the company that would build a lock permitting waterborne commerce between Lake Superior and the other Great Lakes. The Fairbanks Scale Company, which had extensive mining interests in the Upper Peninsula, undertook this challenging construction project in 1853. Within a few years, commerce through the canal had grown to national importance, and the need for new locks became clear. The funds required exceeded the state's capabilities, and thus, in 1881 the locks were transferred to the U.S. government, and were placed under the jurisdiction of the U.S. Army Corps of Engineers. The Corps has operated the locks, toll free, since that time.
The locks are like a series of steps that the ships must make. These "steps" occur when a ship is placed in a lock chamber and water is released or added to the chamber to change its depth (i.e., elevation). With the ship safely floating within the lock chamber, the level of the water moves the ship up or down.
Currently there are four U.S. locks and one smaller Canadian lock. The largest lock, 1,200 feet long and 110 feet wide, was opened in 1969. This new large lock revolutionized lake transport because it could accommodate 1,000-foot vessels, carrying up to 60,000 tons. The shipping industry responded by building 30 new U.S.-flag vessels (including 13 thousand-footers) and lengthening 10 others.
Today, passages through the locks average about 10,000 vessels per year, varying in size from small passenger vessels and workboats to large bulk freighters. Another large lock is in the planning stages and could be built during the next decade if federal and state funding allows.
The St. Lawrence Seaway
The Welland Canal
Graphics: Great Laks system profile courtesy St. Lawrence Seaway Authority; the Soo Locks at Sault Ste. Marie, Mich.; Welland Canal profile courtesy The St. Lawrence Seaway Management Corporation