As of the census[3] of 2000, there were 13,999 people, 5,899 households, and 3,409 families residing in the borough. The population density was 7,614.1 people per square mile (2,937.5/km2). There were 6,071 housing units at an average density of 3,302.0/sq mi (1,273.9/km2). The racial makeup of the borough was 72.06% White, 7.94% African American, 0.11% Native American, 13.63% Asian, 0.09% Pacific Islander, 3.59% from other races, and 2.59% from two or more races. Hispanic or Latino of any race were 8.18% of the population. 8.9% were of Italian, 6.6% Russian, 6.5% Irish, 6.1% Polish and 5.3% German ancestry according to Census 2000. 69.3% spoke English, 7.5% Spanish, 6.3% Chinese, 2.3% Hebrew, 1.9% Russian, 1.2% Hungarian and 1.1% Hindi as their first language.

There were 5,899 households out of which 27.6% had children under the age of 18 living with them, 46.2% were married couples living together, 8.2% had a female householder with no husband present, and 42.2% were non-families. 31.5% of all households were made up of individuals and 9.2% had someone living alone who was 65 years of age or older. The average household size was 2.37 and the average family size was 3.06.

—  Borough —

Highland Park highlighted in Middlesex County. Inset: Location of Middlesex County highlighted in the State of New Jersey.

Census Bureau map of Highland Park, New Jersey

Coordinates: 40°30′1″N 74°25′41″W

In the borough the population was spread out with 21.7% under the age of 18, 8.8% from 18 to 24, 37.1% from 25 to 44, 20.4% from 45 to 64, and 11.9% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 93.3 males. For every 100 females age 18 and over, there were 90.4 males age 18 and over.

The median income for a household in the borough was $53,250, and the median income for a family was $71,267. Males had a median income of $47,248 versus $36,829 for females. The per capita income for the borough was $28,767. About 5.3% of families and 8.4% of the population were below the poverty line, including 7.7% of those under age 18 and 9.6% of those age 65 or over.

The borough supports several active Jewish communities, and in 1978 was one of the first communities in New Jersey to gain an Eruv. Through an arrangement with New Jersey Bell (now Verizon), a continuous wire was strung from pole to pole around the borders of the borough. The wires are inspected every Friday to ensure that the connections are complete. When intact, this Eruv, or symbolic wall, satisfies most Orthodox Jewish religious requirements allowing residents to treat the entire borough as their home during the Sabbath. (The eruv now extends into parts of Edison, New Jersey and New Brunswick, New Jersey.)[9]

Highland Park has at times been a bedroom community for nearby Rutgers University and Johnson & Johnson in New Brunswick, with a resulting academic flair to the community. Nobel laureate Selman Waksman (Medicine, 1952) lived in the borough until he moved to Piscataway in 1954, and laureate Arno Penzias (Physics, 1978) lived in the borough until the 1990s.[citation needed]