As of the census of 2000, there were 14,424 people, 5,136 households, and 3,636 families residing in the town. The population density was 11,811.1 people per square mile (4,564.9/km²). There were 5,254 housing units at an average density of 4,302.2/sq mi (1,662.8/km²). The racial makeup of the town was 66.10% White, 0.98% African American, 0.40% Native American, 11.89% Asian, 0.03% Pacific Islander, 15.96% from other races, and 4.65% from two or more races. Hispanic or Latino of any race were 36.97% of the population.
As of the 2000 census, 7.22% of Harrison's residents identified themselves as being of Chinese ancestry. This was the fifth highest percentage of people with Chinese ancestry in any place in New Jersey with 1,000 or more residents identifying their ancestry.
There were 5,136 households out of which 33.7% had children under the age of 18 living with them, 49.8% were married couples living together, 13.9% had a female householder with no husband present, and 29.2% were non-families. 22.5% 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 2.81 and the average family size was 3.27.
In the town the population was spread out with 21.5% under the age of 18, 10.6% from 18 to 24, 36.8% from 25 to 44, 20.9% from 45 to 64, and 10.3% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 104.0 males. For every 100 females age 18 and over, there were 101.2 males.
The median income for a household in the town was $41,350, and the median income for a family was $48,489. Males had a median income of $33,069 versus $26,858 for females. The per capita income for the town was $18,490. About 10.1% of families and 12.4% of the population were below the poverty line, including 15.5% of those under age 18 and 10.8% of those age 65 or over.
The Harrison station on the PATH rapid transit system offers service to Newark, Jersey City, Hoboken and New York City. The Northeast Corridor, built in the 19th Century by the Pennsylvania Railroad and now owned by Amtrak, carries New Jersey Transit trains, and passes through the city on the same alignment as the PATH. There was a stop on the Northeast Corridor in Harrison, but it was eliminated due to the ease of picking up trains in Newark at Penn Station.
Harrison is served by buses operated by several bus companies. New Jersey Transit offers service within New Jersey on the 39, 40 and 43 routes.
By car, Harrison depends on Interstate 280 which runs through town. Westward, I-280 leads to Route 21, the Garden State Parkway, and Interstate 80. Eastward, it leads to Route 7 and the New Jersey Turnpike.
The closest airport in New Jersey with scheduled passenger service is Newark Liberty International Airport, located 4.8 miles (7.7 km) away in Newark / Elizabeth. New York City's LaGuardia Airport is 20.2 miles (32.5 km) away in Flushing, Queens via the Lincoln Tunnel.