the third largest continent, linked with South America by the Isthmus of Panama and bordering on the Arctic Ocean, the N Pacific, the N Atlantic, the Gulf of Mexico, and the Caribbean. It consists generally of a great mountain system (the Western Cordillera) extending along the entire W coast, actively volcanic in the extreme north and south, with the Great Plains to the east and the Appalachians still further east, separated from the Canadian Shield by an arc of large lakes (Great Bear, Great Slave, Winnipeg, Superior, Michigan, Huron, Erie, Ontario); reaches its greatest height of 6190 m (20 308 ft) in Denali, Alaska, and its lowest point of 86 m (282 ft) below sea level in Death Valley, California, and ranges from snowfields, tundra, and taiga in the north to deserts in the southwest and tropical forests in the extreme south. Pop: 332 156 000 (2005 est). Area: over 24 000 000 sq km (9500 000 sq miles)