Most land in Alaska is in which borough?

The Unorganized Borough is made up of the portions of the U.S. state of Alaska which are not contained in any of its 19 organized boroughs. It encompasses nearly half of Alaska's area, 323,440 square miles (837,700 km2), an area larger than any other U.S. state, and larger than the land area of the smallest 16 states combined. As of the 2000 U.S. Census, it had a population of 81,803, which was 13% of the population of the state.

Unique among the United States, Alaska is not entirely subdivided into organized county equivalents. To facilitate census taking in the vast unorganized area, the United States Census Bureau, in cooperation with the state, divided the unorganized borough into 11 census areas, beginning with the 1970 census. The Petersburg Census Area was made a borough in 2013, leaving ten census areas in the Unorganized Borough:

• Aleutians West Census Area
• Bethel Census Area
• Dillingham Census Area
• Hoonah–Angoon Census Area
• Kusilvak Census Area
• Nome Census Area
• Prince of Wales – Hyder Census Area
• Southeast Fairbanks Census Area
• Valdez–Cordova Census Area
• Yukon–Koyukuk Census Area