Peapack-Gladstone was incorporated as a borough by an Act of the New Jersey Legislature on March 28, 1912, from portions of Bedminster Township, based on the results of a referendum held on April 23, 1912.
Peapack is believed to have been derived from "Peapackton", a Lenape Native American term meaning "marriage of the waters", a reference to the confluence of the Peapack Brook and Raritan River in the area. Gladstone was named in honor of William Ewart Gladstone, who served as British Prime Minister several times between 1868 and 1894.
This town is notable for being a major shooting location of the CBS soap opera Guiding Light since 2008.
As of the census of 2000, there were 2,433 people, 840 households, and 646 families residing in the borough. The population density was 419.5 people per square mile (162.0/km). There were 871 housing units at an average density of 150.2/sq mi (58.0/km). The racial makeup of the borough was 94.45% White, 3.12% African American, 0.08% Native American, 1.23% Asian, 0.70% from other races, and 0.41% from two or more races. Hispanic or Latino of any race were 3.78% of the population.
There were 840 households out of which 37.1% had children under the age of 18 living with them, 69.5% were married couples living together, 5.5% had a female householder with no husband present, and 23.0% were non-families. 18.1% of all households were made up of individuals and 8.5% had someone living alone who was 65 years of age or older. The average household size was 2.71 and the average family size was 3.11.
In the borough the population was spread out with 26.0% under the age of 18, 5.5% from 18 to 24, 30.1% from 25 to 44, 26.3% from 45 to 64, and 12.2% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 97.8 males. For every 100 females age 18 and over, there were 97.0 males.
The median income for a household in the borough was $99,499, and the median income for a family was $118,770. Males had a median income of $62,446 versus $46,500 for females. The per capita income for the borough was $56,542. About 1.9% of families and 4.2% of the population were below the poverty line, including 2.1% of those under age 18 and 4.1% of those age 65 or over.
Gladstone is the terminus of the Gladstone Branch of the Morris and Essex Lines, NJ Transit. Peapack has its own station less than 2 miles before the terminus. By major roads, It is close to I-78 and I-287 and routes 202 and 206.