Phillipsburg was incorporated as a town by an Act of the New Jersey Legislature on March 8, 1861, from portions of Phillipsburg Township (now Lopatcong Township).
The town is located in western New Jersey, on the border of Pennsylvania, and is considered the eastern border of the region's Lehigh Valley.
As of the census of 2000, there were 15,166 people, 6,044 households, and 3,946 families residing in the town. The population density was 4,703.6 people per square mile (1,818.5/km). There were 6,651 housing units at an average density of 2,062.8/sq mi (797.5/km). The racial makeup of the town was 91.84% White, 3.47% African American, 0.12% Native American, 0.83% Asian, 0.01% Pacific Islander, 2.02% from other races, and 1.71% from two or more races. Hispanic or Latino of any race were 5.38% of the population.
There were 6,044 households out of which 31.9% had children under the age of 18 living with them, 43.4% were married couples living together, 16.5% had a female householder with no husband present, and 34.7% were non-families. 29.7% of all households were made up of individuals and 13.9% had someone living alone who was 65 years of age or older. The average household size was 2.49 and the average family size was 3.08.
In the town the population was spread out with 26.6% under the age of 18, 7.9% from 18 to 24, 30.1% from 25 to 44, 20.2% from 45 to 64, and 15.2% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 91.0 males. For every 100 females age 18 and over, there were 85.5 males.
The median income for a household in the town was $37,368, and the median income for a family was $46,925. Males had a median income of $37,446 versus $25,228 for females. The per capita income for the town was $18,452. About 9.9% of families and 13.4% of the population were below the poverty line, including 16.6% of those under age 18 and 11.1% of those age 65 or over.
Many major highways pass through Phillipsburg, including U.S. Route 22, Route 122, and Interstate 78.
New Jersey Transit bus service is provided on the 890 and 891 routes.