[1] The islands form part of the Aleutian Arc of the Northern Pacific Ocean, and occupy a land area of 6,821 sq mi (17,666 km2) that extends westward roughly 1,200 mi (1,900 km) from the Alaskan Peninsula mainland, in the direction of the Kamchatka Peninsula; the archipelago acts as a border between the Bering Sea to the north and the Pacific Ocean to the south.

The axis of the archipelago near the mainland of Alaska has a southwest trend, but at Tanaga Island (about 178° W) its direction changes to the northwest.

This change of direction corresponds to a curve in the line of volcanic fissures that have contributed their products to the building of the islands.

The volcanic Bogoslof and Fire Islands, which rose from the sea in 1796 and 1883 respectively, lie about 30 miles (50 km) west of Unalaska Bay.

[11] According to the Köppen climate classification system, the area southwest of 53°30′N 167°00′W / 53.5°N 167.0°W / 53.5; -167.0, on Unalaska Island, has a "Subpolar Oceanic Climate" (type "Cfc", as does Reykjavík, Tórshavn, Punta Arenas, Ushuaia and the Auckland Islands), characterized by the coldest month averaging above 0 °C (32 °F), one to three months averaging above 10 °C (50 °F), and no significant precipitation differences between seasons.

To the northeast of that point, the climate becomes "Subarctic With Cool Summers And Year Around Rainfall" (type "Dfc", like Petropavlovsk-Kamchatsky, Murmansk, St. Moritz, and Labrador City), where it is similar albeit colder, with the coldest month averaging below 0 °C (32 °F).

Instead of trees, the islands are covered with a luxuriant, dense growth of herbage and shrubs, including crowberry, bluejoint, grasses, sedges, and many flowering plants.

The islands are also frequented by vagrant Asiatic birds, including the common rosefinch, Siberian rubythroat, bluethroat, lanceolated warbler, and the first North American record of the intermediate egret.

[23] The habitats of the Aleutians are largely unspoiled, but wildlife is affected by competition from introduced species such as cattle, caribou, and foxes.

However, the earliest known evidence in public recorded history of human occupation in the Americas is found much farther south.

The early human sites in the Bering Sea were probably submerged by rising waters and sand during the current interglacial period.

The survivors of Bering's party reached the Kamchatka Peninsula in a boat constructed from the wreckage of their ship, and reported the islands were rich in fur-bearing animals.

[11] In the 1780s Russian merchant and seafarer Grigory Shelikhov established a company based on the systematic exploitation of the indigenous peoples, with whom there was sporadic conflict with the native population (frequently disastrous to the poorly armed and vastly outnumbered Russians), for example the Awa'uq Massacre.

The colonies soon entered a relatively stable state based on cooperation, intermarriage, and official policies that provided social status, education, and professional training to children of mixed Aleut-Russian birth.

Reversing the usual trend in colonization where indigenous technologies are replaced, the Russians adopted the Aleut kayak, or baidarka, sea otter hunting techniques, and the working of native copper deposits.

The Russians instituted public education, preservation of the Aleut language through transliteration of religious and other texts into Aleut via an adaptation of the Cyrillic alphabet, vaccination of the native population against smallpox, and science-based sea mammal conservation policies that were ahead of their time.

During his third and last voyage in 1778, Captain James Cook surveyed the eastern portion of the Aleutian archipelago, accurately determined the position of some of the more important islands, and corrected many errors of former navigators.

New buildings included a Methodist mission and orphanage, and the headquarters for a considerable fleet of United States revenue cutters, which patrolled the sealing grounds of the Pribilof Islands.

During World War II, in what were the only two invasions of the United States during the war, small parts of the Aleutian islands were occupied by Japanese forces, when Attu and Kiska were invaded possibly to divert American forces away from the main Japanese attack at Midway Atoll.

The U.S. Navy, having broken the Japanese naval codes, proceeded as if this was just a diversion,[27][28][29] and it did not expend large amounts of effort in defending the islands.

The invasion was an embarrassment for the Allied forces as the entire Japanese force of 5,183 men had left the island on July 28 without the Americans noticing; however, the Americans suffered significant casualties during their “invasion” – 313 men died as a result of accidents, with many dying due to accidental fire.

A rumor spread that FDR had accidentally left his Scottish Terrier "Fala" on one of the Islands and had to send a destroyer to retrieve the dog, costing taxpayers several million dollars.

The President made fun of these rumors during a talk with the Teamsters Union in Washington DC, now known as the "Fala Speech".

The governor of Alaska ordered state flags lowered to half-staff to honor the 43 Americans who died during the two-day Japanese air attack in 1942.

The Aleutian World War II National Historic Area Visitors Center opened that month.

The U.S. conducted underground tests of nuclear weapons on Amchitka Island from 1965 to 1971 as part of the Vela Uniform program.