The City of Unalaska is the main population center in the Aleutian Islands. The city is in the Aleutians West Census Area, a regional component of the Unorganized Borough in the U.S. state of Alaska. Unalaska is located on Unalaska Island and neighboring Amaknak Island in the Aleutian Islands off mainland Alaska. The population was 4,254 at the 2020 census, which is 81% of the entire Aleutians West Census Area. Unalaska is the second-largest city in the Unorganized Borough, behind Bethel.