Peapack-Gladstone was incorporated as a borough on March 28, 1912, from portions of Bedminster Township. 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.
