The Town of Southold is one of ten towns in Suffolk County, New York, United States. It is located in the northeastern tip of the county, on the North Fork of Long Island. The population was 21,968 at the 2010 census. The town also contains a hamlet named Southold, which was settled in 1640.
The town is at the northeastern end of Long Island, New York on a peninsula called the North Fork and its extensions Plum Island, and Fishers Island. The Long Island Sound separates the town from Connecticut. The eastern end of the peninsula, near Orient Point, is north of the Town of Shelter Island, but the town is separated from the South Fork of Long Island by the Great Peconic Bay and the Little Peconic Bay. The western end of the town is the border of the Town of Riverhead. It is twenty-one miles from Orient Point to the border with Riverhead. Robins Island, a protected open space in Great Peconic Bay, is also part of the Town of Southold.
According to the United States Census Bureau, the town has a total area of 404.5 square miles (1,047.6 km²), of which, 53.7 square miles (139.1 km²) of it is land and 350.8 square miles (908.5 km²) of it (86%) is water. The town has approximately 163 linear miles of coastline.
Significant coastal fish and wildlife habitats within the Town of Southold, include: the Mattituck Inlet Wetlands and Beaches, Fishers Island Beaches, Pine Islands and Shallows, the Goldsmith Inlet and Beach, Pipes Cove Creek and Moores Drain, the Dumpling Islands and Flat Hammock.
As of the census of 2000, there were 20,599 people, 8,461 households, and 5,804 families residing in the town. The population density was 383.5 people per square mile (148.1/km²). There were 13,769 housing units at an average density of 256.3 per square mile (99.0/km²). The racial makeup of the town was 93.53% White, 2.91% Black or African American, 0.07% Native American, 0.45% Asian, 0.07% Pacific Islander, 1.51% from other races, and 1.47% from two or more races. Hispanic or Latino of any race were 4.77% of the population.
There were 8,461 households out of which 26.5% had children under the age of 18 living with them, 56.8% were married couples living together, 8.5% had a female householder with no husband present, and 31.4% were non-families. 26.6% of all households were made up of individuals and 15.1% had someone living alone who was 65 years of age or older. The average household size was 2.40 and the average family size was 2.90.
In Southold town the population was spread out with 21.5% under the age of 18, 5.2% from 18 to 24, 23.8% from 25 to 44, 26.5% from 45 to 64, and 23.1% who were 65 years of age or older. The median age was 45 years. For every 100 females, there were 93.3 males. For every 100 females age 18 and over, there were 90.2 males.
The median income for a household in the town was $49,898, and the median income for a family was $61,108. Males had a median income of $46,334 versus $31,440 for females. The per capita income for the town was $27,619. About 4.1% of families and 5.8% of the population were below the poverty line, including 7.2% of those under age 18 and 5.4% of those age 65 or over.