Unalaska (, ) is the chief center of population 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 4,376 at the 2010 census, which is 79% of the entire Aleutians West Census Area. Unalaska is the second largest city in the Unorganized Borough, behind Bethel.