Inland waterway is a body of water used for transportation within a continent. Inland waterways range in scale from individual rivers to complex systems of connected rivers, lakes, and artificial canals. Barges, ships, and recreational boats travel by inland waterway.
Shipping by inland waterway generally costs less but takes longer than shipping by airplane, train, or truck. For this reason, shippers use inland waterways to move large, bulky cargoes, including chemicals, coal, construction materials, grains, minerals, and petroleum products. On the Mississippi River, for example, single tugboats commonly transport 15 barges, each capable of carrying about 1,500 tons (1,360 metric tons) of cargo. In some cases, a single tugboat can transport more than 40 barges. Aside from sightseers, few passengers travel long distances by inland waterway because such travel is slow.
Most inland waterways follow natural rivers because constructing long artificial canals is expensive. However, most natural rivers are too shallow or too rough and choppy to be traveled by large ships. Engineers have made long stretches of rivers more navigable by deepening the channels and eliminating sharp curves. Most importantly, engineers make rivers more navigable by building dams. Dams raise the water level upstream, allowing larger ships to use the waterway. They also enable engineers to control the flow of a river. Dams can help maintain higher water levels during dry seasons. They can also prevent rivers from becoming too rough following periods of heavy rain or melting snow.
To enable ships to travel past dams, engineers often build devices called locks. A lock is a water-filled chamber with a gate at each end. After a ship enters a lock, the water level can be raised to match the water level upstream of the dam or lowered to match the level downstream. Engineers also build locks to enable boats to travel safely through areas of changing elevation. See Canal (Canal locks) .
Inland waterways can freeze during severe winters. When this happens, waterway managers must either halt service or use ice-breaking ships to clear a channel.
The main inland waterways of North America are (1) the Mississippi River together with its tributaries and (2) the Great Lakes together with the St. Lawrence Seaway. The Mississippi River and its tributaries include more than 10,000 miles (16,000 kilometers) of navigable waterway. The St. Lawrence Seaway enables large ships from the Atlantic Ocean to enter the Great Lakes, reaching as far inland as Chicago and Duluth, Minnesota. The Illinois River links the Mississippi River with the Great Lakes. The Welland Ship Canal, which forms part of the St. Lawrence Seaway, connects Lakes Erie and Ontario in Canada. It allows ships to pass around Niagara Falls.
Many rivers around the world serve as important inland waterways. These include the Columbia and Snake rivers in North America; the Amazon and Parana rivers in South America; the Nile River in Africa; the Yangtze River in Asia; and the Danube, Rhine, and Volga rivers in Europe. Canals connect some major European rivers, such as the Volga and Don rivers and the Danube and Rhine rivers. These canals allow inland waterway transportation over long distances across the continent.
