In 1919, the New Jersey State Highway Commission built a new road that became part of the Lincoln Highway, an early plan to create a transcontinental highway. The stretch was constructed on the west side of the Pennsylvania Railroad (now the Northeast Corridor) from near the northeast of Dow Avenue between Colonia and Iselin to Cedar Street in Menlo Park, to avoid two railroad crossings. The old road is now Middlesex-Essex Turnpike and Thornall Street, on the east side of the tracks.
As of the census of 2000, there were 17,811 people, 6,184 households, and 5,077 families residing in the CDP. The population density was 1,772.4/km² (4,594.1/mi²). There were 6,254 housing units at an average density of 622.3/km² (1,613.1/mi²). The racial makeup of the CDP was 86.00% White, 4.76% African American, 0.10% Native American, 6.31% Asian, 0.06% Pacific Islander, 1.27% from other races, and 1.50% from two or more races. Hispanic or Latino of any race were 4.97% of the population.
There were 6,184 households out of which 35.0% had children under the age of 18 living with them, 68.7% were married couples living together, 10.3% had a female householder with no husband present, and 17.9% were non-families. 15.2% of all households were made up of individuals and 8.7% had someone living alone who was 65 years of age or older. The average household size was 2.88 and the average family size was 3.21.
In the CDP the population was spread out with 23.7% under the age of 18, 6.2% from 18 to 24, 29.1% from 25 to 44, 24.8% from 45 to 64, and 16.2% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 93.0 males. For every 100 females age 18 and over, there were 88.4 males.
The median income for a household in the CDP was $67,372, and the median income for a family was $76,090. Males had a median income of $50,260 versus $36,657 for females. The per capita income for the CDP was $27,732. About 1.5% of families and 2.2% of the population were below the poverty line, including 2.0% of those under age 18 and 4.0% of those age 65 or over.