Its western coastline is limited by the Chukchi Sea, while its eastern shores (beyond Point Barrow) are in the Beaufort Sea.
The North Slope Borough is the largest county-level political subdivision in the United States by area, with a larger land area than that of the state of Utah. Although the adjacent Yukon-Koyukuk Census Area is larger in area, it has no borough-level government. The borough is also the third-least densely populated county-level entity in the United States (after the Yukon-Koyukuk Census Area and the Lake and Peninsula Borough).
It also shares its eastern border with the Yukon Territory, Canada, which has no subdivisions.

There were 2,109 households out of which 48.10% had children under the age of 18 living with them, 43.3% were married couples living together, 18.3% had a female householder with no husband present, and 27.70% were non-families. 21.4% of all households were made up of individuals and 1.9% had someone living alone who was 65 years of age or older. The average household size was 3.45 and the average family size was 4.05.
In the borough the population was spread out with 38.2% under the age of 18, 9.50% from 18 to 24, 30.1% from 25 to 44, 18.10% from 45 to 64, and 4.2% who were 65 years of age or older. The median age was 27 years. For every 100 females there were 112.50 males. For every 100 females age 18 and over, there were 113.90 males.