Hackettstown was incorporated as a town by an Act of the New Jersey Legislature on March 9, 1853, from portions of Independence Township. Portions of territory were exchanged with Mansfield Township in 1857, 1860, 1872 and 1875.
Hackettstown houses the headquarters of Transistor Devices Incorporated and Mars Chocolate USA, the American division of Mars, Incorporated, makers of Milky Way, Mars, M&M's, Twix and Snickers candy bars, as well as pet foods (such as the well-known Whiskas and Pedigree brands), human foods (including Uncle Ben's) and non-confectionery snack foods (including Combos).
It is believed that Hackettstown was named after Samuel Hackett, a prominent landowner who is said to have "contributed liberally to the liquid refreshments on the christening of a new hotel, in order to secure the name which, before this, had been Helms' Mills or Musconetcong".
Hackettstown was named #72 of the top 100 towns in the United States to Live and Work In by Money Magazine in 2005, it has not been included since.
As of the census of 2000, there were 10,403 people, 4,134 households, and 2,530 families residing in the town. The population density was 2,809.5 people per square mile (1,085.6/km²). There were 4,347 housing units at an average density of 1,174.0/sq mi (453.6/km²). The racial makeup of the town was 90.25% White, 2.18% African American, 0.12% Native American, 2.91% Asian, 0.06% Pacific Islander, 2.00% from other races, and 2.47% from two or more races. Hispanic or Latino of any race were 8.01% of the population.
There were 4,134 households out of which 30.2% had children under the age of 18 living with them, 48.0% were married couples living together, 9.3% had a female householder with no husband present, and 38.8% were non-families. 31.7% of all households were made up of individuals and 11.0% had someone living alone who was 65 years of age or older. The average household size was 2.41 and the average family size was 3.10.
In the town the population was spread out with 22.7% under the age of 18, 10.0% from 18 to 24, 33.9% from 25 to 44, 21.2% from 45 to 64, and 12.2% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 92.8 males. For every 100 females age 18 and over, there were 89.6 males.
The median income for a household in the town was $51,955, and the median income for a family was $64,383. Males had a median income of $44,420 versus $31,110 for females. The per capita income for the town was $24,742. About 2.3% of families and 4.8% of the population were below the poverty line, including 4.9% of those under age 18 and 7.1% of those age 65 or over.
The Hackettstown station is the western terminus of the New Jersey Transit Morristown Line and the Montclair-Boonton Line, which both provide service to Hoboken Terminal or to Pennsylvania Station in Midtown Manhattan via Midtown Direct.
NJ Transit bus service is provided on the MCM5 and 973 routes.
Passing through Hackettstown are U.S. Route 46, Route 57 and Route 182.
Hackettstown is located 49.3 miles from Newark Liberty International Airport in Newark, Elizabeth. Lehigh Valley International Airport near Allentown, Pennsylvania is 39.0 miles away. A small general aviation airport, named Hackettstown Airport and holding the official database designation of (FAA LID: N05) is in adjoining Mansfield Township, only a few hundred yards from the municipal border with Hackettstown proper.