Trans-Alaska Pipeline, pipeline that connects the oil fields of Prudhoe Bay in northern Alaska, U.S., with the harbour at Valdez, 800 miles (1,300 km) to the south.
The discovery of oil on Alaska’s North Slope in 1968 spurred the creation of a safe and efficient way to bring those reserves to market. Atlantic Richfield Company, British Petroleum (now BP PLC), and Humble Oil (a subsidiary of Exxon Corporation) agreed to build a pipeline that would connect the North Slope to Valdez, an ice-free port on Prince William Sound (an embayment of the Gulf of Alaska). The movement of oil through the 48-inch (1.2-metre) pipe would be boosted by pumping stations situated along its length, ensuring a constant flow at roughly 4 miles (6 km) per hour. At this rate, oil would complete the journey from Prudhoe Bay to Valdez in about nine days.
A series of environmental impact studies were commissioned, and their results led to changes in the pipeline’s design—notably that about half of the pipeline would be elevated to prevent the heated oil in it from thawing the permafrost and to allow wildlife to pass more easily under it. Portions of the pipeline were also to be buried where necessary, in part to facilitate the movement of wildlife. Other special construction measures included installing devices to dissipate heat buildup in permafrost ground around pipeline-support trestles and building bridges for the pipeline across rivers and streams to avoid burying the pipeline at those locations.
On Nov. 16, 1973, Pres. Richard M. Nixon signed the Trans-Alaska Pipeline Authorization Act into law, and much of the next year was spent building access roads along the proposed route (the Dalton Highway now parallels the entire pipeline). Construction on the $8 billion pipeline began on March 27, 1975. The final weld was completed at Pumping Station 3, near Atigun Pass, on May 31, 1977, and oil began to flow through the pipeline on June 20. However, a series of mechanical problems halted the pipeline’s operation, and oil did not arrive at Valdez until July 28.
In spite of these difficulties, production continued, and the pipeline moved its billionth barrel of oil in early 1980. Attention was focused on the southern terminus of the pipeline in 1989 when the tanker Exxon Valdez ran aground in Prince William Sound. Images of oil-slicked sea birds and otters provided stark examples of the dangers of an oil spill in the Arctic. Though of a smaller scale than the Exxon Valdez disaster, the largest spill in the history of the pipeline occurred in 2006 when a transit pipe at BP’s Prudhoe Bay facility ruptured. More than a quarter million gallons (one million litres) of oil spilled onto the tundra, and Prudhoe Bay production was halved as engineers spent months replacing corroded pipe.
Alaska was admitted to the Union as the 49th state on January 3, 1959.
What are some major geographical features of Alaska?
Alaska features Mount McKinley (Denali), the highest peak in North America, as well as numerous fjords and inlets. It also has extensive tundra and permafrost areas.
What is the main economic activity in Alaska?
Alaska’s economy is primarily based on oil production, fishing, federal and state expenditures (military and civilian), research and development, and tourism.
What was the impact of the Exxon Valdez oil spill?
The Exxon Valdez oil spill in 1989 released about 250,000 barrels of oil into Prince William Sound, causing major ecological and economic damage. Exxon paid a $900 million settlement for the cleanup efforts.
Alaska is central to the great circle route connecting North America with Asia by sea and air and is equidistant from most of Asia and Europe. That central location has made Alaska militarily significant since the Japanese invasion of the Aleutians in 1942 during World War II. Alaska’s eastern border with Canada is about 1,538 miles (2,475 km) long, more than one-third the length of the entire U.S. boundary with Canada (3,987 miles [6,416 km]). Alaska’s western maritime boundary, separating the waters of the United States and Russia, was established in the Treaty of Cession of 1867 (which declared the transfer of Alaska from Russia to the United States). The roughly 1,000-mile (1,600-km) de facto boundary runs through the Chukchi Sea and the Bering Strait to a point between Alaska’s St. Lawrence Island and Russia’s Chukotskiy (Chukchi) Peninsula and to the southwest, between Attu Island, the westernmost island of the Alaskan Aleutian chain, and the Russian Komandor Islands. The boundary leaves a patch of international waters, known as the “Doughnut Hole,” in the Bering Sea. Off the extreme western end of the state’s Seward Peninsula, Little Diomede Island, part of Alaska, lies in the Bering Strait only 2.5 miles (4 km) from Russian-owned Big Diomede Island. Both Russia and the United States have shown a tacit tolerance of unintentional airspace violations, which are common in bad weather.
The name Alaska is derived from the Unangax (Aleut) word alaxsxa or alaxsxix, both meaning “mainland” or “great land.” Indeed, Alaska has an immense area and a great variety of physical characteristics. Aside from its mainland peninsula, the state includes about 15,000 square miles (38,800 square km) of fjords and inlets and about 34,000 miles (54,400 km) of indented tidal coastline. In addition, most of the continental shelf of the United States lies along Alaska’s coast. In the Alaska Range north of Anchorage is Mount McKinley (Denali), 20,310 feet (6,190 meters) high—the highest peak in North America. Nearly one-third of the state lies within the Arctic Circle, and about four-fifths of Alaska is underlain by permafrost (permanently frozen sediment and rock). Tundra—the vast treeless Arctic plains—makes up about half of the state’s surface area. The southern coast and the panhandle at sea level are fully temperate regions. In those and in the adjoining Canadian areas, however, lies the world’s largest expanse of glacial ice outside Greenland and Antarctica. Rimming the state on the south is one of Earth’s most active earthquake belts, the circum-Pacific seismic belt. Alaska has more than 130 active volcanoes, most of which are on the Aleutian Islands and the adjacent Alaska Peninsula. The Alaska earthquake of 1964 was one of the most powerful earthquakes recorded in the United States.
Upon attaining statehood, Alaska increased the size of the United States by nearly one-fifth. The new area included vast stretches of unexplored land and untapped resources. Its settlement and exploitation have been hindered by its distance from the rest of the country and by geographic and climatic impediments to travel and communications; Alaska continues to be the country’s last frontier. About half of the state’s inhabitants live in the Greater Anchorage–Kenai Peninsula area.
Exxon Valdez oil spill: cleanupWorkers steaming blast rocks covered in crude oil leaking from the Exxon Valdez, an oil tanker that ran aground in Prince William Sound, Alaska, U.S.
The difficulty of finding a balance between conservation and development in an enormous land has been ongoing since the beginning of the 20th century. Alaska’s residents and the state and federal governments have had to make delicate decisions on such major issues as a natural gas pipeline project, Alaska Natives’ land claims, the creation of national parks and wildlife refuges, noncommercial whaling by Indigenous peoples, and related matters. One of the major conflicts occurred in the late 1960s and early 1970s between conservationists and petroleum companies over the proposed Trans-Alaska Pipeline, which now runs from the oil-rich North Slope on the Arctic Ocean to Valdez, in the south. The debate intensified following a catastrophic oil spill in 1989, when the tanker Exxon Valdez released some 250,000 barrels of oil into Prince William Sound. Moreover, beginning in the 1980s, the two sides came into conflict over whether to permit drilling in the Arctic National Wildlife Refuge. In the early 21st century the question of drilling in the 23-million-acre (9.3-million-hectare) National Petroleum Reserve–Alaska on the Arctic coastal plain and on the continental shelves of the Beaufort and Chukchi seas also became controversial issues. Area 665,384 square miles (1,723,337 square km). Population (2020) 733,391; (2024 est.) 740,133.
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Lynch, Donald, Miller, Maynard M.. "Alaska". Encyclopedia Britannica, 19 Feb. 2025, https://www.britannica.com/place/Alaska. Accessed 11 June 2025.
