Annandale is an unincorporated community and census-designated place (CDP) located within Clinton Township, in Hunterdon County, New Jersey, United States. As of the 2010 United States Census, the CDP's population was 1,695. The Annandale Historic District was listed on the state and national registers of historic places in 1994.
According to the United States Census Bureau, Annandale had a total area of 1.452 square miles (3.760 km2), all of which was land.
The 2010 United States Census counted 1,695 people, 658 households, and 455 families in the CDP. The population density was 1,167.6 inhabitants per square mile (450.8/km2). There were 692 housing units at an average density of 476.7 per square mile (184.1/km2). The racial makeup was 86.61% (1,468) White, 2.48% (42) Black or African American, 0.35% (6) Native American, 7.32% (124) Asian, 0.00% (0) Pacific Islander, 0.77% (13) from other races, and 2.48% (42) from two or more races. Hispanic or Latino of any race were 4.66% (79) of the population.
Of the 658 households, 38.8% had children under the age of 18; 56.4% were married couples living together; 9.6% had a female householder with no husband present and 30.9% were non-families. Of all households, 25.2% were made up of individuals and 7.8% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.15.
27.7% of the population were under the age of 18, 5.7% from 18 to 24, 27.3% from 25 to 44, 31.3% from 45 to 64, and 8.1% who were 65 years of age or older. The median age was 39.1 years.