Oak Island, North Carolina is a town located mostly on Oak Island (which also contains the town of Caswell Beach and the North Carolina Baptist Assembly at Fort Caswell) in Brunswick County, North Carolina; a small part of the town extends onto the mainland north of the island's bridge. The population was 6,571 at the 2000 census. It was founded in 1999 by the consolidation of the towns of Long Beach and Yaupon Beach. Its main industry is tourism; the town has an average summer population of 30-40,000.
According to the United States Census Bureau, the town has a total area of 9.1 square miles (23.6 km²).8.0 square miles (20.6 km²) of it is land and 1.1 square miles (3.0 km²) of it (12.61%) is water. Oak Island has approximately 28 miles of coastline.
There were 3,076 households out of which 18.3% had children under the age of 18 living with them, 59.4% were married couples living together, 6.4% had a female householder with no husband present, and 31.7% were non-families. 25.3% of all households were made up of individuals and 9.9% had someone living alone who was 65 years of age or older. The average household size was 2.14 and the average family size was 2.51.
In the town the population was spread out with 15.0% under the age of 18, 5.3% from 18 to 24, 22.3% from 25 to 44, 36.4% from 45 to 64, and 21.0% who were 65 years of age or older. The median age was 49 years. For every 100 females there were 95.2 males. For every 100 females age 18 and over, there were 93.5 males.
The median income for a household in the town was $40,496, and the median income for a family was $48,775. Males had a median income of $30,656 versus $24,759 for females. The per capita income for the town was $23,964. About 4.8% of families and 8.0% of the population were below the poverty line, including 8.7% of those under age 18 and 6.9% of those age 65 or over.