What is the biggest borough in Alaska?

Alaska is not organized into counties. It is divided into boroughs and census areas.

The largest borough is the North Slope Borough (in northern Alaska and includes the city of Barrow) which covers a total area of about 88,000 square miles and sports a total population of about 7,500. The largest census area is the Yukon-Koyukuk Census Area (in central Alaska and includes the area surrounding Fairbanks) which covers a total area of about 146,000 square miles and is home for about 6,500 people.

Neither of these are the most populous areas, however. The City/Borough of Anchorage has about 260,000 people. The Fairbanks/North Star Borough has about 83,000. The Mat-Su Borough (which includes the cities of Palmer and Wasilla) has about 59,000.