Alaska is a U.S. state situated in the northwest extremity of the North American continent. Bordering the state to the east is the Canadian Yukon Territory and the province of British Columbia, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia (specifically, Siberia) further west across the Bering Strait. Alaska is the largest state in the United States by area, the 4th least populous and the least densely populated of the 50 United States. Approximately half of Alaska's 731,449 residents live within the Anchorage metropolitan area. Alaska's economy is dominated by the oil, natural gas, and fishing industries, resources which it has in abundance. Tourism is also a significant part of the economy.
Although it had been occupied for thousands of years by indigenous peoples, from the 18th century onward, European powers considered the territory of Alaska ripe for exploitation. The United States purchased Alaska from Russia on March 30, 1867, for $7.2 million ($120 million adjusted for inflation) at approximately two cents per acre ($4.74/km²). The area went through several administrative changes before becoming organized as a territory on May 11, 1912. It was admitted as the 49th state of the U.S. on January 3, 1959.
The name "Alaska" had been introduced in the Russian colonial period, when it was used to refer to the peninsula. It was derived from an Aleut idiom, which figuratively refers to the mainland of Alaska. Literally, it means object to which the action of the sea is directed. It is also known as Alyeska, the "great land", an Aleut word derived from the same root.