Hainesport Township was incorporated as a township by an Act of the New Jersey Legislature on March 12, 1924, from portions of Lumberton Township.
As of the census of 2000, there were 4,126 people, 1,477 households, and 1,150 families residing in the township. The population density was 632.8 people per square mile (244.3/km²). There were 1,555 housing units at an average density of 238.5/sq mi (92.1/km²). The racial makeup of the township was 94.09% White, 2.67% African American, 0.10% Native American, 1.70% Asian, 0.51% from other races, and 0.95% from two or more races. Hispanic or Latino of any race were 2.13% of the population.
There were 1,477 households out of which 35.7% had children under the age of 18 living with them, 67.5% were married couples living together, 7.2% had a female householder with no husband present, and 22.1% were non-families. 17.5% of all households were made up of individuals and 8.3% had someone living alone who was 65 years of age or older. The average household size was 2.78 and the average family size was 3.16.
In the township the population was spread out with 26.3% under the age of 18, 5.7% from 18 to 24, 31.4% from 25 to 44, 24.9% from 45 to 64, and 11.8% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 95.7 males. For every 100 females age 18 and over, there were 94.5 males.
The median income for a household in the township was $66,417, and the median income for a family was $72,005. Males had a median income of $49,015 versus $33,932 for females. The per capita income for the township was $28,091. About 2.0% of families and 3.0% of the population were below the poverty line, including 3.1% of those under age 18 and 5.2% of those age 65 or over.
New Jersey Transit provides bus service to Philadelphia on the 317 and 413 routes.