Canals and Locks

A canal is an artificial waterway built with the purpose of moving ships, goods, and/or people. The term can refer to an inland waterway that allows for intra- or inter-urban transportation, such as those in Venice, Suzhou, and throughout the Low Countries. Alternatively, it may refer to an artificial channel that connects two previously unconnected bodies of water.

The first examples of canals date back to premodern times. Mesopotamian societies dug canals for irrigation and flood control as early as the 4th or 5th millennium b.c.e. Evidence of irrigation canals by Indus Valley, Nile Valley, Sumerian, and Inca civilizations is also available, and the existence of an extensive network of canals under the Roman Empire is confirmed by the remnants of stone aqueducts found throughout southern Europe. China's Grand Canal, which connects the cities of Beijing and Hangzhou, was commenced in the 5th century b.c.e. and completed in the 7th century c.e. and remains the world's longest artificial waterway. From the outset, the Grand Canal has been a significant artery of commerce in China and remains so to this day.

On a relatively small scale, canal traffic has been an integral component of overland goods transport in Asia and Europe for over a millennium. However, the Industrial Revolution was the impetus for the large-scale expansion of canals throughout Europe and North America in the late 18th and early 19th centuries. Though Europe's canal network was initially better formed, the westward expansion of the United States' population drove the development of numerous canals, such as the Erie Canal and the Chesapeake & Ohio, which in turn dramatically reduced commercial transport costs. This system of internal waterways led to the early growth and development of several major cities, including Buffalo and Chicago.

However, as railways began to undermine waterborne modes of overland transport, many canals began to lose their commercial utility. The most significant canals of today are those that play a key role in global shipping, such as Egypt's Suez Canal, which connects the Indian Ocean basin to the Atlantic basin, and the Panama Canal, which connects the Pacific Ocean to the Caribbean basin and ultimately the Atlantic. While the completion of major transcontinental railroads and highways has all but replaced intracontinental ship traffic, globalization and an increasingly spatially fragmented division of labor ensure that intercontinental maritime traffic has increased greatly, particularly in the wake of the formation of the World Trade Organization (WTO) and the advent of containerization.