(Covers information from Anderson's universe)
Alaska was the largest areal state in the United States, bordering the Province of Yukon, Canada to the East and the Russian Federation to the West by a maritime border in the Bering Strait. It was once believed to be the location of the human safe haven, Arcadia.
As revealed by a journal discovered by Alice, Alaska was believed to be the last remaining safe haven for humanity in the aftermath of the global outbreak. Various messages as received by radio transmissions described the state as "safe" and "loving" It's frozen environment and cool temperatures and its isolation from any populated area made it an ideal environment for survivors looking to escape the growing numbers of zombies. Though doubtful in the beginning of Arcadia's existence, Claire Redfield eventually led the survivors of her convoy, to Alaska in search of the haven.
After going against Umbrella, Alice traveled to Alaska hoping to find Claire and the other survivors; instead, she found a desolate and seemingly deserted area populated by planes, suggesting that other survivors heard the transmission for Arcadia. She later discovered the Umbrella helicopter the survivors used abandoned near a shoreline and the journal on the pilot's seat. After searching the airplane graveyard, Alice encountered an amnesiac Claire who attacked her. When she failed to help Claire remember what happened to the others, the two departed from Alaska in her plane and headed for Los Angeles.
Ironically enough, despite the promise of Arcadia being different then expected, Alaska actually did appear to have escaped the ravages of the T-virus; there was no sign of reanimated humans or animals and there were vast expanses of lush forest and greenery. This was in stark contrast to the rest of the Earth, where most expanses of forest and fresh water had disappeared due to the virus.
The idea for Alaska to be a save haven came from Anderson's time in Alien vs Predator, which was set in Antarctica. In the commentary, Anderson also recalled Resident Evil CODE:Veronica.