semicircular canal: see ear.

lock, canal, stretch of water enclosed by gates, one at each end, built into a canal or river for the purpose of raising or lowering a vessel from one water level to another. A lock may also be built into the entrance of a dock for the same purpose. When the ship is to be raised to a higher level, it enters the lock and a gate is closed behind it. Water is let into the lock until its level equals that of the water ahead. The forward gate is then opened, and the ship progresses on the higher level. The procedure is reversed when the vessel is to pass from a higher to a lower level. As many locks as necessary are used in a given waterway. Most modern locks are made of concrete, although some have walls of steel-sheet piles or floors of natural rock or sand. The mitre gate, frequently used in the United States, consists of two swinging sections forming an arc or shallow V, with the apex pointed toward high water so that water pressure keeps both sections tightly sealed when closed. Another type of gate in common use consists of one piece of sheet steel that slides across the entrance to the lock on rollers or is lifted into the air or sunk underwater. The gates of most locks are operated by hydraulic or electric power. Water is poured into or out of locks through culverts built into the masonry structure of the lock walls. Among well-known locks are those of the Panama Canal.

canal, an artificial waterway constructed for navigation or for the movement of water. The digging of canals for irrigation probably dates back to the beginnings of agriculture, and traces of canals have been found in the regions of ancient civilizations. Canals are also used to provide municipal and industrial water supplies. The drainage of wet lands may be accomplished by means of a canal; by this method the Fens of England and the Zuider Zee in the Netherlands were drained. Canals can be used for flood control by diverting water from threatened areas into storage basins or to other outlets. In some cases canals are used to generate electricity; the Moscow-Volga Canal is used for this purpose.

Navigation canals developed after irrigation canals and for a long time were level, shallow cuts or had inclined planes up which vessels were hauled from one level to the next; locks (see lock, canal) developed separately in China (10th cent.) and Europe (Holland; 13th cent.). Over the years canals have been expanded in width and depth in order to accommodate larger craft, and they have, in some cases, been constructed to form bridges or to pass through tunnels to overcome topographic difficulties. Movement on canals was long accomplished by animal tows or by poling; in the 20th cent. mechanized tows and self-propelled barges appeared.

The Grand Canal of China (the longest in the world) was completed in the 13th cent. and is the most notable of the early canals. France, Belgium, Holland, and Germany were the first in Europe to develop inland waterway systems by using canals to connect rivers; these countries now have a dense network of waterways (see Rhine Canals; Midland Canal). Canal building was widespread in the 18th and 19th cent. During that period England developed an elaborate canal network, and there was also a canal-building boom in the United States in the 19th cent., especially after the completion of the Erie Canal. However, the rise of railroads brought a decline in the building and use of canals as inland waterways. Canals have been built to shorten sea voyages or to make them less hazardous, e.g., the Suez Canal, the Panama Canal, and the Kiel Canal. Canals improve conditions on natural waterways by bypassing falls (the Welland Ship Canal), shallows, or swift currents (the Sip Canal in the Danube River's Iron Gate gorge). Canals may provide inland cities with direct access to the sea (the Manchester Ship Canal), or shorten the distance between cities (the Albert Canal). In the 20th cent. canals regained importance, as modern technology provided the means to overcome greater topographic obstacles and facilitated the construction of larger canals and the expansion of existing ones. The Great Lakes-Saint Lawrence Seaway system, opened to navigation in 1959, is the world's longest deep-draft inland waterway. Including six short canals with a total length of less than 60 nautical mi (110 km), it extends from the Atlantic Ocean to Duluth, Minn. on Lake Superior, a distance of more than 2,340 mi (3,700 km), providing large oceangoing vessels passage into central North America.

alimentary canal: see digestive system.

Welland Ship Canal, 27.6 mi (44.4 km) long, SE Ont., Canada, connecting Lake Ontario with Lake Erie and bypassing Niagara Falls. Built between 1914 and 1932 by Canada to replace a canal opened in 1829, it can accommodate (minimum depth 27 ft/8 m) the largest lake ships. Its eight locks overcome a 326-ft (99-m) difference in level between the lakes. The Lake Ontario entrance is near Port Dalhousie; the Lake Erie entrance is at Port Colborne. It is part of the St. Lawrence Seaway system.

Trent Canal, waterway system, 240 mi (386 km) long, S Ont., Canada, connecting Lake Ontario, from the Bay of Quinte, with Lake Huron at Georgian Bay; built 1833-48. It utilizes the Trent River to Rice Lake, the Otonabee River through Peterborough, the Kawartha Lakes and artificial channels to Lake Simcoe and Lake Couchiching, and the Severn River to Georgian Bay. The system, with numerous dams and locks, has only 20 mi (32 km) of artificial channels. It was designed primarily to shorten the shipping route between lakes Ontario and Huron but has proved more valuable as a source of water power. Used mainly by pleasure craft, it is open to navigation from May to October.

Suez Canal, Arab. Qanat as Suways, waterway of Egypt extending from Port Said to Port Tawfiq (near Suez) and connecting the Mediterranean Sea with the Gulf of Suez and thence with the Red Sea. The canal is somewhat more than 100 mi (160 km) long. Proceeding S from Port Said, it runs in an almost undeviating straight line to Lake Timsah. From there a cutting leads to the Bitter Lakes (now one body of water), and a final cutting then reaches the Gulf of Suez. The canal has no locks and can accommodate all but the largest ships.

The desirability of a water connection between the Mediterranean and the Red Sea was long appreciated in antiquity. A canal was built in the 20th or 19th cent. B.C. to Lake Timsah (then the northern end of the Red Sea). Xerxes I had the canal extended. It was restored several times (notably by Ptolemy II and Trajan) until the 8th cent. A.D., when it was closed and fell into disrepair.

The modern canal was planned by the French engineer Ferdinand de Lesseps, who also supervised construction (1859-69). Great Britain, which had opposed the construction of the canal, became the largest shareholder in 1875 by purchasing the interest of the Egyptian khedive. The Convention of Constantinople signed in 1888 by all major European powers of the time declared the canal neutral and guaranteed free passage to all in time of peace and war. Great Britain was the guarantor of the neutrality of the canal; management was placed in the hands of the Suez Canal Company.

Under the Anglo-Egyptian treaty of 1936, which made Egypt virtually independent, Britain reserved rights for the protection of the canal, but after World War II, Egypt pressed for evacuation of British troops from the area. Egypt in 1951 repudiated the 1936 treaty, and anti-British rioting and clashes on the border of the zone erupted. In 1954, Britain agreed to withdraw, and in June, 1956, the British completed their evacuation of armed forces from Egypt and the canal zone.

After Great Britain and the United States withdrew their pledges of financial support to help Egypt build the Aswan High Dam (see under Aswan), Egyptian President Gamal Abdal Nasser nationalized (July, 1956) the Suez Canal and set up the Egyptian Canal Authority to replace the existing privately owned company. In August, British oil and embassy officials were expelled from the country. Having been denied passage through the canal since 1950 and having suffered repeated border raids from Egypt, Israel, with French and English air support, invaded Egyptian territory on Oct. 29, 1956. Within a few days France and Great Britain sent armed forces to retake the Suez Canal. Intervention by the United Nations brought an armistice in early November, and a UN emergency force replaced the British and French troops. The canal, blocked for more than six months because of damage and sunken ships, was cleared with UN help and reopened in Apr., 1957. Egypt agreed to pay, in six annual installments, approximately $81 million to shareholders of the nationalized Suez Canal Company; final payment was made on Jan. 1, 1963.

Despite UN efforts to guarantee the free passage of vessels through the canal, Egypt prevented Israeli ships from using the waterway. The canal was closed by Egypt during the Arab-Israeli War of 1967, after which it formed part of the boundary between Egypt and the Israeli-occupied Sinai peninsula. Egypt lost considerable revenue as a result of the closing of the canal, but friendly Arab countries agreed to subsidize the Egyptian economy with contributions roughly equaling the former income from the canal. After the Suez Canal was closed, many ships (especially tankers) were built that were too large for the canal, and alternate sea routes were used increasingly in world trade.

In Oct., 1973, Egyptian troops crossed the canal and attacked Israeli forces on the east bank of the canal; Israeli units crossed the canal to the west and eventually encircled the Egyptian Third Army. In early 1974, Egypt and Israel signed an agreement that led to Israeli withdrawal from the Sinai. With both banks of the canal again secured, Egypt, with the assistance of the U.S. navy, cleared it of mines and war wreckage, and it was reopened in 1975. Traffic declined in the 1980s, largely because of high fees and water too shallow for oil supertankers. In 1997 officials announced fee reductions and a plan to deepen the channel.

Rideau Canal, 126 mi (203 km) long, S Ont., Canada, connecting the Ottawa River at Ottawa with Lake Ontario at Kingston. The canal, which has 47 locks, follows the course of the Rideau River. It was built (1826-32) by army engineers under the direction of Col. John By to provide access from the St. Lawrence to Lake Ontario without exposure to attack by American forces on the U.S. shore of the St. Lawrence. Little used as a commercial waterway, the canal system has become a popular recreation area and scenic attraction.

Panama Canal Zone, former territory within Panama, 553 sq mi (1,432 sq km), that was administered by the United States under a 1903 treaty (with later amendments) with Panama. The zone included the Panama Canal and an area extending 5 mi (8.1 km) on each side. Under the terms of a later treaty (1977), the zone was abolished in Oct., 1979, and returned to Panamanian rule; the canal itself was ceded to Panama in 1999. Panama has begun turning former military installations into housing, civilian ports, hotels, industrial parks, universities, and sports facilities. Some bases have been converted into tourist complexes aimed at attracting cruise-ship passengers, while some undeveloped areas have become eco-tourist sites. The northern section of the former territory is now part of Colón prov., and the southern section part of Panamá prov. Cristóbal, Balboa (Caribbean and Pacific ports, respectively), and Ancon are the chief towns.

Panama Canal, waterway across the Isthmus of Panama, connecting the Atlantic (by way of the Caribbean Sea) and Pacific oceans, built by the United States (1904-14) on territory leased from the republic of Panama. The canal, running S and SE from Limón Bay at Colón on the Atlantic to the Bay of Panama at Balboa on the Pacific, is 40 mi (64 km) long from shore to shore and 51 mi (82 km) long between channel entrances. The Pacific terminus is 27 mi (43 km) east of the Caribbean terminus. The minimum depth is 41 ft (12.5 m).

From Limón Bay a ship is raised by Gatún Locks (a set of three) to an elevation 85 ft (25.9 m) above sea level, traverses Gatún Lake, then crosses the Continental Divide through Gaillard (formerly Culebra) Cut and is lowered by Pedro Miguel Lock to Miraflores Lake and then by the Miraflores Locks (a set of two) to sea level. The average tidal range on the Atlantic side is less than a foot (.3 m); that on the Pacific side is 12.6 ft (3.8 m).

U.S. Interest in a Canal

Building an interoceanic canal was suggested early in Spanish colonial times. The United States, interested since the late 18th cent. in trading voyages to the coast of the Pacific Northwest, became greatly concerned with plans for a canal after settlers had begun to pour into Oregon and California. Active negotiations led in 1846 to a treaty, by which the republic of New Granada (consisting of present-day Panama and Colombia) granted the United States transit rights across the Isthmus of Panama in return for a guarantee of the neutrality and sovereignty of New Granada.

The isthmus gained more importance after the United States acquired (1848) California and the gold rush began, and the trans-Panama RR was built (1848-55) with U.S. capital. At the same time, interest in an alternate route, the Nicaragua Canal, was strong in both Great Britain and the United States. Rivalry between the two countries was ended by the Clayton-Bulwer Treaty (1850), which guaranteed that neither power should have exclusive rights or threaten the neutrality of an interoceanic route. In the 1870s and 80s the United States tried unsuccessfully to induce Great Britain to abrogate or amend the Clayton-Bulwer Treaty.

After the United States acquired territory in the Caribbean and in the Pacific as a result of the Spanish-American War (1899), U.S. control over an isthmian canal seemed imperative. Following protracted negotiations, a U.S.-British agreement (see Hay-Pauncefote Treaties) was made in 1901, giving the United States the right to build, and by implication fortify, an isthmian canal. It was then necessary for Congress to choose between Nicaragua or Panama as the route for the canal.

French Attempts

Meanwhile a concession for building a sea-level canal in Panama (granted 1878) was acquired by a French company under Ferdinand de Lesseps. Work began in 1881, but poor planning, disease among the workers, construction troubles, and inadequate financing drove the company into bankruptcy in 1889. Amid charges of corruption and mismanagement, French courts transferred (1894) the rights and assets to a new company. Although the alternate Nicaragua route was favored by the United States, an American representative of the French company, William Nelson Cromwell, began working vigorously to interest the United States in the Panama route, and Philippe Bunau-Varilla, a leading figure in the new company, devoted himself to the cause. When a U.S. commission recommended a canal through Nicaragua in 1901, Bunau-Varilla persuaded the French directors to reduce the price of the company's rights, gaining the support of Mark Hanna and later of the new President, Theodore Roosevelt. The commission reversed its recommendation, and Congress authorized purchase of the French company's rights and construction of the Panama Canal.

Insurrection against Colombia

The Hay-Herrán Treaty, signed (Jan., 1903) with Colombia, would have given the United States a strip of land across the Isthmus of Panama in return for an initial cash payment of $10 million and an annuity of $250,000, but the Colombian senate refused to ratify it. An insurrection, involving Bunau-Varilla and other proponents of the canal as well as the regional population, was encouraged by the United States. Panama rose in revolt on Nov. 3, 1903, declaring itself independent of Colombia. Invoking the treaty of 1846, the United States sent an American warship to Panama, and its presence prevented Colombian troops from quelling the outbreak. The new republic was formally recognized three days later, and on Nov. 17 the Hay-Bunau-Varilla Treaty was signed, granting to the United States, in return for the same terms offered Colombia, exclusive control of a canal zone in perpetuity, other sites necessary for defense, and sanitary control of Panama City and Colón. Colombia's efforts to secure redress for the loss of Panama later resulted in ratification of a treaty (1921) by which the United States paid Colombia $25 million, and Colombia recognized the independence of Panama.

Construction and Improvements

Construction of a lock canal was decided on in 1906. The first three years were spent in the development of construction facilities, surveys, and disease control. The canal was informally opened Aug. 15, 1914; formal dedication took place on July 12, 1920. The total cost was $336,650,000, and c.240 million cu yd (184 million cu m) of earth were evacuated. Madden Dam, which stores additional water for the locks, was completed in 1935.

In 1939 treaty amendments increased Panama's annuity to $434,000 (retroactive to 1934 to offset dollar devaluation), provided for a transisthmian highway, and (at Panama's insistence) abrogated the U.S. guarantee of the neutrality and sovereignty of Panama. Although in the same year Congress authorized construction of a third set of locks, World War II intervened, and the plans were shelved. In 1955 the annuity was raised to $1,930,000, and the United States undertook to build a high-level bridge (completed 1962) over the Pacific side of the canal. The Gaillard Cut was widened in 1969 to permit two-way traffic. The largest modern merchant and fighting ships, however, cannot pass through the canal.

Panamanian Control

In the 1960s there was increasing agitation in Panama to achieve greater Panamanian control over the canal, resulting in the negotiation of a new treaty (1967) which failed, however, to gain ratification by the Panamanian government. In 1977 negotiations were successful, and a new treaty was signed. It returned the Panama Canal Zone to Panama while setting up joint U.S.-Panamanian control of the canal until the end of 1999, when Panama gained full control. A separate treaty (1979) guarantees the permanent neutrality of the canal. In 0ct., 2006, Panamanian voters approved a plan for expanding the canal by adding a third series of locks paralleling the existing locks; the new locks, which the plan calls for constructing from 2008 to 2012, would be larger, enabling wider, longer vessels with deeper drafts to transit the Isthmus. The plan would utilize the work begun but abandoned on a third series of locks prior to World War II.

Ohio and Erie Canal, former waterway of Ohio, 307 mi (494 km) long, between Lake Erie at Cleveland and the Ohio River at Portsmouth; built 1825-32. It utilized part of the courses of the Cuyahoga, Muskingum, and Scioto rivers and had 49 locks. It flourished as a means of transporting freight until the advent of the railroad era in the 1850s. The canal was responsible for the growth of cities along its route, especially Cleveland, Akron, and Columbus.

Nicaragua Canal, proposed waterway between the Atlantic and the Pacific oceans. It would be 172.8 mi (278 km) long and would generally follow the San Juan River, then go through Lake Nicaragua near the southern shore and across the narrow isthmus of Rivas to the Pacific Ocean. First proposed by Henry Clay, the U.S. secretary of state in 1826, the route was an important factor in negotiation of the Clayton-Bulwer Treaty (1850). In later times the route has been considered as an adjunct to the Panama Canal; it would shorten the water distance between New York and San Francisco by nearly 500 mi (805 km).

Under the Bryan-Chamorro Treaty (1916), the United States paid Nicaragua $3 million for an option in perpetuity and free of taxation, including 99-year leases to the Corn Islands and a site for a naval base on the Gulf of Fonseca. Costa Rica protested that Costa Rican rights to the San Juan River had been infringed, and El Salvador maintained that the proposed naval base affected both it and Honduras. Both protests were upheld by the Central American Court of Justice. The court rulings were ignored by Nicaragua and the United States. The action was bitterly criticized by Latin Americans and others as an example of U.S. imperialism.

New York State Canal System, waterway system, 524 mi (843 km) long, traversing New York state and connecting the Great Lakes with the Finger Lakes, the Hudson River, and Lake Champlain. The waterway, a modification and improvement of the old Erie Canal and its branches, was authorized (1903) by public vote. Work was begun in 1905 and was completed in 1918, when it was opened as the New York State Barge Canal. The system was given its present name in 1992.

The main sections are the Erie Canal, extending west from Waterford opposite Troy on the Hudson to Tonawanda on the Niagara River; the Champlain Canal, joining the Erie Canal at Troy extending north to Whitehall on Lake Champlain; the Oswego Canal, connecting the Erie Canal at Three Rivers with Oswego on Lake Ontario to the north; and the Cayuga-Seneca Canal, joining the Erie Canal with Cayuga and Seneca lakes to the south. The canals (12 ft/3.7 m deep), with 57 electrically operated locks, can accommodate 2,000-ton vessels and, unlike the original Erie Canal, include large sections of canalized rivers and lakes in the waterway. Commercial shipping had all but disappeared from the waterway by the 1990s, and leisure craft now predominate in the waterway's traffic. In an effort to improve recreational facilities and increase tourism along the canal, a major renovation of the system was undertaken in the late 1990s.

New York State Barge Canal: see New York State Canal System.

Midland Canal, Ger. Mittelland Kanal, artificial waterway system of Germany, extending eastward c.200 mi (320 km) along the North German plain from the Dortmund-Ems Canal, Germany, to Magdeburg, Germany, on the Elbe River. An eastward extension of the Midland Canal passes through Berlin and connects with the Oder River. The system is made up of a series of canals that join parallel north-flowing rivers. The canal facilitates east-west transportation of raw materials and manufactured goods, with coal and iron constituting a large portion of the barge traffic.

Manchester Ship Canal, 35.5 mi (57 km) long with a minimum depth of 28 ft (8.5 m), connecting Manchester, W England, with the Mersey estuary at Eastham, above Birkenhead. Begun in 1887, it was opened in 1894 and changed Manchester from a river port to a seaport.

Lynn Canal, natural inlet, c.90 mi (145 km) long, 7-12 mi (11-19 km) wide, SE Alaska. It connects in the S with Chatham Strait and Stephens Passage and thrusts north between mountains to break finally into the inlets of the Chilkoot and Chilkat rivers. Navigable to its head, Lynn Canal connects Skagway with Juneau and is an important shipping lane. During the Alaska gold rush (1896) it was a major route to the gold fields.

Love Canal, section of Niagara Falls, N.Y., that formerly contained a canal that was used as chemical disposal site. In the 1940s and 50s the empty canal was used by a chemical and plastics company to dump nearly 20,000 tons (c.18,000 metric tons) of toxic waste; the waste was sealed in metal drums in a manner that has since been declared illegal. The canal was then filled in and the land given to the expanding city of Niagara Falls by the chemical company. Housing and an elementary school were built on the site. By the late 1970s several hazardous chemicals had leaked through their drums and risen to the surface. Investigations confirmed the existence of toxins in the soil and determined that they were responsible for the area's unusually high rates of birth defects, miscarriages, cancer, illness, and chromosome damage. Families were evacuated from the area in 1978, and in 1980 the Love Canal area was declared a national emergency.

The disaster led to the creation of the Environmental Protection Agency's "Superfund," which makes responsible parties liable for the cleanup of environmental hazards. More than $20,000,000 in settlement damages was paid by the chemical company and the city of Niagara Falls to a group of former residents. The company also agreed in 1994 to pay New York state $98 million and in 1995 to pay the federal government $129 million toward the costs incurred during the cleanup of the area. The evacuated neighborhood was repopulated in the 1990s after the cleanup was completed.

Kiel Canal, artificial waterway, 61 mi (98 km) long, in Schleswig-Holstein, N central Germany, connecting the North Sea with the Baltic Sea. At sea level, the canal extends from Kiel on the Baltic to Brunsbüttelkoog at the mouth of the Elbe River. Locks at each end of the canal minimize tidal variation. Built (1887-95) to facilitate movement of the German fleet, the Kiel Canal was widened and deepened from 1905 to 1914. Large oceangoing ships can pass through the canal. Because of its great military and commercial importance the canal was internationalized by the Treaty of Versailles (1919), though its direct administration was left with the Germans. Hitler repudiated its international status in 1936, but free navigation in the canal was returned after World War II. The canal is also known as the Kaiser Wilhelm Canal, for William II of Germany, and as the North Sea-Baltic Canal (Ger. Nord-Ostsee-Kanal). Today the canal is a major passage for shipping in the Baltic region.

Kaiser Wilhelm Canal: see Kiel Canal.

Grand Canal, Chinese Da Yunhe [large transit river], longest in the world, extending c.1,000 mi (1,600 km) from Beijing to Hangzhou, E China, and forming an important north-south waterway on the North China Plain. The canal was started in the 6th cent. B.C. and was constructed over a 2,000-year period. Its largest sections were completed in A.D. 610 under Emperor Yang Ti of the Sui dynasty and were built by dredging and linking existing canals. Tree-shaded roads, postal stations, and imperial pavilions were built along the canal. Between the 10th and the early 13th cent. the waterway fell into disrepair. Kublai Khan reconstructed the canal in the 13th cent. and extended it to Beijing. Improvements were made during the Ming dynasty (1368-1644). Today the canal follows the Bai River south from Beijing to Tianjin. The 250-mi (412-km) section S of Tianjin, which ties into the Wei River, is navigable in all seasons by junks and small steamers. Leaving the Wei, the canal runs through the elongated lakes of Shandong prov. past Su-chou, where it crosses the Chang at Zhenjiang. It runs generally south through the Chang delta, past Wuxi and on to Hangzhou, the southern terminus. The canal is 100 to 200 ft (30-61 m) wide and from 2 to 15 ft (.6-4.6 m) deep. Railroads, roads, and widespread silting have reduced its economic importance.

Erie Canal, artificial waterway, c.360 mi (580 km) long; connecting New York City with the Great Lakes via the Hudson River. Locks were built to overcome the 571-ft (174-m) difference between the level of the river and that of Lake Erie. With its three branch canals it forms the New York State Canal System.

After the American Revolution, the need for an all-American water route between the Great Lakes and the Atlantic coast was evident. Political unity, easy and inexpensive transportation, and increased trade (free from Canadian competition) were the anticipated benefits of such a route. Several land surveys followed, and by 1810, the issue was paramount in the New York legislature, where De Witt Clinton lent his political support. A canal commission, including Clinton, Gouverneur Morris, Stephen Van Rensselaer, and Thomas Eddy, recommended (1811) a canal to Lake Erie rather than to Lake Ontario. The canal bill, drawn up by Clinton in 1815, was debated in the legislature (1816-17), with New York City and the Lake Ontario interests opposing it vigorously. Although a presidential veto of a national waterway project forced the proposed canal's financial burden on New York alone, the canal bill passed the state legislature in Apr., 1817.

Work on the canal was carried on by gangs made up, in many cases, of European immigrants. The canal's course was entirely enclosed; streams and lakes were not incorporated into the waterway. The middle section (Utica to Salina) was completed in 1820; the eastern section through the Mohawk River valley was finished in 1823. Elaborate celebrations opened the entire canal in 1825; Clinton and other notables sailed from Buffalo to New York City, where Clinton emptied a barrel of Lake Erie water into the Atlantic Ocean. The canal was enlarged beginning in 1835; its most important branches, the Champlain (opened 1819), the Oswego (1828), and the Cayuga-Seneca (1829), were also enlarged. The Erie Canal contributed to New York City's financial development, opened eastern markets to Midwest farm products and encouraged immigration to that region, and helped to create numerous large cities. Its initial success started a wave of canal building in the United States.

Railroad competition, beginning in the 1850s, eventually destroyed the canal's long-haul advantages; however, for many years the Erie Canal was a profitable route. Tolls were abolished in 1882, however, because of its state of disrepair and to lure more traffic. Although some improvements were made (1884-94), inadequate navigability, the competition of Canadian routes, and the disclosure of fraudulent administration (the "Canal Ring") brought about plans for complete renovation and subsequent conversion (1905-18) into a large, modern barge canal. Unlike the original canal, the revamped waterway incorporated canalized rivers and lakes in the waterway; parallel sections of the old Erie Canal were abandoned. Much tonnage was still shipped via the canal in the 1950s, but the opening of the New York State Thruway and the St. Lawrence Seaway sealed the canal's commercial demise. Traffic now consists almost entirely of pleasure boats; a five-year overhaul in the late 1990s was undertaken to make the canal a major "recreationway."

Dortmund-Ems Canal, waterway, 165 mi (266 km) long, NW Germany, from Dortmund to Emden. Built from 1892 to 1899, it connects the industrial Ruhr district with the Ems River and the North Sea. It is connected to the Rhine River by two canals.

Delaware and Raritan Canal, abandoned canal, 45 mi (72 km) long, between Bordentown and New Brunswick, N.J., connecting the Delaware and the Raritan rivers; opened in 1834. Once an important inland waterway, it was superseded by the railroads in the latter half of the 19th cent.

Delaware and Hudson Canal, former waterway, 108 mi (174 km) long, between Honesdale, Pa., and Eddyville, N.Y. (now in Kingston), linking the Delaware and Hudson rivers; built 1825-28 to move coal from the Pennsylvania fields to New York markets. A gravity railroad, completed across the Moosic Mts. in 1829, connected the coalfields at Carbondale, Pa., with Honesdale. Four suspension bridge aqueducts were later constructed along the canal, including one over the Delaware that still survives. The canal operated profitably until the 1860s; increasing railroad competition caused its abandonment in 1898.

Chicago Sanitary and Ship Canal: see Chicago, river.

Chesapeake and Ohio Canal, former waterway, c.185 mi (300 km) long, from Washington, D.C., to Cumberland, Md., running along the north bank of the Potomac River. A successor to the Potomac Company's (1784-1828) navigation improvement project, the Chesapeake and Ohio Canal was planned to extend W to Pittsburgh. Work was begun in 1828, but financial and labor problems (leading in 1834 to the first use of federal troops to settle a labor dispute), as well as opposition from the rival Baltimore and Ohio RR, delayed completion to Cumberland until 1850. Although extension to Pittsburgh proved impractical, the canal experienced a busy period in the 1870s carrying coal from the Cumberland mines. The canal was used until it was damaged by floods in 1924; in 1938 it was sold to the U.S. government. Partially restored, the canal and its towpath were proclaimed a national monument in 1961 and in 1971 became a national historical park (see National Parks and Monuments, table).

Chesapeake and Delaware Canal, sea-level canal, 19 mi (31 km) long, 250 ft (76 m) wide, and 27 ft (8.2 m) deep, connecting the head of Chesapeake Bay with the Delaware River. Built in 1824-29, the canal was bought by the federal government in 1919 and later was enlarged and modernized. It is part of the Intracoastal Waterway and can accommodate oceangoing vessels.

Canal, Antonio: see Canaletto.

Canal du Midi, canal, c.150 mi (240 km) long, linking Sète and Toulouse, S France. It was built to carry oceangoing ships between the Atlantic Ocean and the Mediterranean Sea, but because of its size it now carries only barge traffic.

Canal Zone: see Panama Canal Zone.

Caledonian Canal, waterway, c.60 mi (100 km) long, cutting across Highland, N Scotland, from Moray Firth to Loch Linnhe by way of the Great Glen. It was built in two phases (1803-22 and 1843-47; opened 1822) to save shallow-draft vessels the circuitous route around N Scotland. Of the waterway, 38 mi (61 km) consists of the natural waters of Lochs Ness, Oich, and Lochy. The canal has 29 locks and is used primarily for fishing and leisure boating.

All-American Canal, 80 mi (129 km) long, SE Calif.; part of the federal irrigation system of the Hoover Dam. Built between 1934 and 1940 across the Colorado Desert, the canal is entirely within the United States and replaces the Inter-California Canal, which passes through Mexico. The Imperial Dam, NE of Yuma, Ariz., diverts water from the Colorado River into the All-American Canal, which runs W to Calexico, Calif. Smaller canals move water into the Imperial Valley; the Coachella Canal branches NW to the Coachella Valley. This canal system irrigates more than 630,000 acres (254,961 hectares) and has greatly increased crop yield in the area; however, problems of drainage and salinity exist.

Albert Canal, waterway, c.80 mi (130 km) long, N Belgium, from the Meuse River to the Scheldt River; constructed 1930-39. The canal connects the important industrial region around Liège with the port of Antwerp, Belgium.

Artificial waterway built for transportation, irrigation, water supply, or drainage. The early Middle Eastern civilizations probably first built canals to supply drinking and irrigation water. The most ambitious navigation canal was a 200-mi (320-km) construction in what is now Iraq. Roman canal systems for military transport extended throughout northern Europe and Britain. The most significant canal innovation was the pound lock, developed by the Dutch c. 1373. The closed chamber, or pound, of a lock is flooded or drained of water so that a vessel within it is raised or lowered in order to pass between bodies of water at different elevations. Canals were extremely important before the coming of the railroad in the mid-19th century. Among the significant waterways in the U.S. were the Erie Canal, several canals linking the Great Lakes, and one connecting the Great Lakes to the Mississippi River. Modern waterway engineering enables larger vessels to travel faster by reducing delays at locks. See also Grand Canal, Panama Canal, Suez Canal.

Learn more about canal with a free trial on Britannica.com.

End portion of the alimentary canal, distinguished from the rectum by the transition from an internal mucous membrane layer to one of skinlike tissue and by its narrower diameter. Waste products move from the rectum to the anal canal. The human anal canal is 1–1.5 in. (2.5–4 cm) long and has three parts: upper, with longitudinal folds (rectal columns); lower, with involuntary and voluntary constrictive muscles (sphincters) to control discharge of feces; and the anal opening itself. Enlargements of the ends of rectal and anal veins are called hemorrhoids.

Learn more about anal canal with a free trial on Britannica.com.

Canal, southeastern Ontario, Canada. Linking Lake Huron with Lake Ontario, the canal extends from the southeastern shore of Georgian Bay up the Severn River to Lake Simcoe, connects several lakes of the Kawartha Lake region to Rice Lake, and passes down the Trent River to the Bay of Quinte and Lake Ontario. Its 242-mi (389-km) main course consists of 33 mi (53 km) of man-made channels and 42 locks. Construction began in 1833. The waterway once served a busy lumber trade; it is now a popular tourist attraction.

Learn more about Trent Canal with a free trial on Britannica.com.

Ship canal, Isthmus of Suez, Egypt. Connecting the Red Sea with the eastern Mediterranean Sea, it extends 101 mi (163 km) from Port Said to the Gulf of Suez and allows ships to sail directly between the Mediterranean and the Indian Ocean. Built by the French-owned Suez Canal Co., it was completed in 1869 after a decade of construction. Its ownership remained largely in French and British hands until Egypt nationalized it in 1956, setting off an international crisis (see Suez Crisis). It has a minimum width of 179 ft (55 m) and a depth of about 40 ft (12 m) at low tide. Though protected by international treaty, the canal has been closed twice. The first closing was during the Suez Crisis. The canal was closed again by the Six-Day War (1967) and remained inoperative until 1975. It is one of the world's most heavily used shipping lanes.

Learn more about Suez Canal with a free trial on Britannica.com.

or Panama Canal Zone

Strip of territory, a historic administrative entity in Panama over which the U.S. formerly exercised jurisdictional rights (1903–79). The zone came into being in 1904 when Panama granted the U.S., in return for annual payments, sole right to operate and control the Panama Canal, including a strip of land 10 mi (16 km) wide along the canal extending from the Atlantic to the Pacific Ocean and bisecting the Isthmus of Panama. The zone was abolished by treaty in 1979, and civil control of the territory was returned to Panama. By the same treaty a commission under joint U.S.-Panamanian ownership was established to operate the canal until the year 2000, when Panama assumed full control.

Learn more about Canal Zone with a free trial on Britannica.com.

Lock-type canal, Panama. Extending across the Isthmus of Panama, it connects the Atlantic and Pacific oceans. It is about 50 mi (82 km) long from deepwater to deepwater, with an average depth of 43 ft (13 m). The width varies between 500 to 1,000 ft (150 to 300 m). In 1881 a French company began constructing the canal, but the enterprise collapsed in 1889. Under a 1903 treaty Panama granted the U.S. the Panama Canal Zone and the rights to build and operate a canal. Work began in 1904; facing enormous obstacles, George Washington Goethals directed the construction from 1907, and the canal opened on Aug. 15, 1914. The canal enabled ships traveling between the two oceans to avoid the lengthy circumnavigation of South America and was a boon to world commerce. After disputes over sovereignty, a 1977 treaty provided for Panama to take control of the canal by 2000; it did so in 1999. Except for small craft, no vessel can pass through the canal under its own power. Ships are towed by electric locomotives, and it generally takes 15–20 hours to complete the passage (including waiting time). Sets of double locks enable ships to pass in opposite directions simultaneously.

Learn more about Panama Canal with a free trial on Britannica.com.

Deep fjord, southeastern Alaska, U.S. An important gateway to the Klondike region, it is 80 mi (129 km) long and 6 mi (10 km) wide. The northernmost fjord to penetrate the Coast Mountains, it was named in 1794 by Capt. George Vancouver for his birthplace, King's Lynn, Eng.

Learn more about Lynn Canal with a free trial on Britannica.com.

Neighbourhood in Niagara Falls, N.Y., the site of the worst environmental disaster involving chemical wastes in U.S. history. Originally the site of an abandoned canal, it became a dumping ground for nearly 22,000 tons of chemical waste in the 1940s and '50s. The canal was later filled in, and housing was built on it. The leakage of toxic chemicals into these homes was detected in 1978, and residents were discovered to have a high incidence of chromosome damage. After their evacuation, 1,300 former residents obtained a $20 million settlement from the dumping company and the city. In the early 1990s New York state ended its cleanup and declared parts of the area safe for residence.

Learn more about Love Canal with a free trial on Britannica.com.

Series of waterways in northern China that link Hangzhou with Beijing. Some 1,085 mi (1,747 km) in length, it is the world's longest man-made waterway. It was build to enable successive Chinese regimes to transport surplus grain from the agriculturally rich Yangtze (Chang) and Huai river valleys to feed the capital cities and large standing armies in the north. The oldest portion, in the south, may date from the 4th century BC. Expanded over the centuries, it continues to be used today for shipping and irrigation.

Learn more about Grand Canal with a free trial on Britannica.com.

Historic waterway, northern U.S. It stretches from Buffalo, N.Y., on Lake Erie to Albany, N.Y., on the Hudson River. Commissioned by Gov. DeWitt Clinton of New York, it opened in 1825. It connected the Great Lakes with New York City and contributed greatly to the settlement of the Midwest, allowing for the transport of people and supplies. Enlarged several times, the canal is 363 mi (584 km) long, 150 ft (46 m) wide, and 12 ft (3.6 m) deep. Now used mainly for pleasure boating, it is part of the New York State Canal System.

Learn more about Erie Canal with a free trial on Britannica.com.

Park, eastern U.S. It consists of the former Chesapeake and Ohio Canal, a waterway running along the Potomac River between Washington, D.C., and Cumberland, Md. The canal, which extends 185 mi (297 km), was built beginning in the 1820s. Competition from the railroads later caused its economic decline. The canal was purchased in 1938 by the U.S. government; it was restored and established as a historical park in 1971.

Learn more about Chesapeake and Ohio Canal National Historical Park with a free trial on Britannica.com.