Dayton is an unincorporated community and census-designated place (CDP) located within South Brunswick, in Middlesex County, New Jersey, United States. At the 2010 United States Census, the CDP's population was 7,063.
Dayton has a post office with its own ZIP code (08810) that encompasses the entire CDP, as well as some surrounding areas. The community was named for William L. Dayton, a local attorney who later served in the United States Senate or for Jonathan Dayton, the youngest person to sign the United States Constitution, who later served as a United States Senator from New Jersey. The area had been known as Cross Roads and was renamed in 1866 to avoid confusion with mail that was sent to another post office that shared the name.
According to the United States Census Bureau, the CDP had a total area of 2.102 square miles (5.443 km2), including 2.099 square miles (5.436 km2) of land and 0.003 square miles (0.007 km2) of water (0.13%).
The 2010 United States Census counted 7,063 people, 2,288 households, and 1,901 families in the CDP. The population density was 3,365.0 inhabitants per square mile (1,299.2/km2). There were 2,347 housing units at an average density of 1,118.2 per square mile (431.7/km2). The racial makeup was 40.15% (2,836) White, 9.19% (649) Black or African American, 0.18% (13) Native American, 46.00% (3,249) Asian, 0.01% (1) Pacific Islander, 1.63% (115) from other races, and 2.83% (200) from two or more races. Hispanic or Latino of any race were 5.78% (408) of the population.
Of the 2,288 households, 52.8% had children under the age of 18; 70.0% were married couples living together; 10.4% had a female householder with no husband present and 16.9% were non-families. Of all households, 13.5% were made up of individuals and 3.9% had someone living alone who was 65 years of age or older. The average household size was 3.09 and the average family size was 3.44.
30.1% of the population were under the age of 18, 7.3% from 18 to 24, 29.8% from 25 to 44, 27.1% from 45 to 64, and 5.7% who were 65 years of age or older. The median age was 36.0 years.