The Unorganized Borough is composed of the portions of the U.S. state of Alaska which are not contained in any of its 19 organized boroughs. While referred to as the "Unorganized Borough", it is not a borough itself, as it forgoes that level of government structure. It encompasses nearly half of Alaska's land area, 323,440 square miles (837,700 km2), and, as of the 2020 U.S. Census, it had a population of 77,157, which was 10.52% of the population of the state. The largest communities in the Unorganized Borough are the cities of Bethel, Unalaska, and Valdez.

Bethel is a city in the U.S. state of Alaska, located on the Kuskokwim River approximately 50 miles (80 km) from where the river discharges into Kuskokwim Bay. It is the largest community in western Alaska and in the Unorganized Borough and the eighth-largest in the state. Bethel has a population of 6,325 as of the 2020 census, up from 6,080 in 2010.