Yukon (yōˈkŏn) [key], river, c.2,000 mi (3,220 km) long, rising in Atlin Lake, NW British Columbia, Canada, and receiving numerous headwater streams; one of the longest rivers of North America. It flows generally northwest, into Yukon past Dawson and across the Alaska border, to Fort Yukon, thence generally southwest through central Alaska until, in a wide swing north, it enters Norton Sound of the Bering Sea through a delta that is 60 mi (97 km) wide. Its chief tributaries are the Teslin, Pelly, White, Stewart, Porcupine, Tanana, and Koyukuk rivers. The river is incised in the Yukon Plateau; marshy land borders much of its upper course. The Yukon is navigable for river boats three months of the year to Whitehorse, c.1,775 mi (2,860 km) upstream.
The Yukon basin is one of the most sparsely populated and least developed regions of North America. Much of its history, exploration, and development centers on the river system. Its lower reaches were explored (1836–37, 1843) by Russians, and in 1843 Robert Campbell of the Hudson's Bay Company explored the upper course. During the Klondike gold rush (1897–98) the Yukon was a major route to the gold fields. Greater development of the basin occurred in the mid-1900s due to its strategic location, and several military installations were later built.
The Yukon River is a major salmon-spawning ground, and salmon fishing is an important seasonal activity. The Yukon is used to generate hydroelectricity, but it remains one of the greatest undeveloped hydroelectric resources in North America. On the river's banks are fur-trading posts, missions, native villages, and towns with modern airports serving vast areas.