Plainsboro was incorporated as a township on May 6, 1919, from lands north of Plainsboro Road and Dey Road that had been part of South Brunswick Township and lands south of Plainsboro Road and Dey Road that had been part of Cranbury Township.[19] The main impetus towards the creation of the township was the lack of schools serving the area; a new school was constructed after the township was established, which still exists as J.V.B. Wicoff School, named for one of the individuals who led the effort to create Plainsboro.[20]

What is now Barnegat Township was originally incorporated as Union Township on March 10, 1846, from portions of both Dover Township (now Toms River Township) and Stafford Township, while the area was still part of Monmouth County. It became part of the newly formed Ocean County on February 15, 1850. Portions of the township were taken to form Lacey Township (March 23, 1871), Ocean Township (April 13, 1876), Harvey Cedars (December 13, 1894) and Long Beach Township (March 23, 1899).[21] Union Township changed its name to Barnegat Township as of January 1, 1977.[21]

South Plainfield was incorporated by an act of the New Jersey Legislature on March 12, 1926, from portions of Piscataway Township, based on the results of a referendum passed on April 6, 1926.[21] The borough’s name derives from Plainfield, which derived its name from a local estate[22] or from its scenic location.[23]

Medford was incorporated as a township by an act of the New Jersey Legislature on March 1, 1847, from portions of Evesham Township, based on the results of a referendum held that day. Portions of the township were taken to form Shamong Township (February 19, 1852), Lumberton Township (March 14, 1860) and Medford Lakes (May 17, 1939).[20] Geographically, the township is part of the South Jersey region.

West Milford started out as New Milford in what was then western Bergen County in the 18th century, having been settled by disenchanted Dutch from Milford, New Jersey (later renamed by the British as Newark). These same Dutch also built a town of New Milford in eastern Bergen County. When both New Milfords applied for post offices in 1828, a clerk in Washington, D.C. is said to have approved the other application first and assigned the name “West Milford” to the New Milford in western Bergen County in order to distinguish between the two locations.[20]

The area known as Scotch Plains was first settled by Europeans, including many Scottish Quakers as early as 1684.[20] The name is said to have come from George Scott, a leader of a group of Scottish settlers.[21] It later served as a stop on the stage coach line between New York City and Philadelphia.

Carteret was originally created as the borough of Roosevelt on April 11, 1906, from portions of Woodbridge Township, based on the results of a referendum approved on May 22, 1906.[15] The name was changed to Carteret as of November 7, 1922. The borough was also called Carteret during the period from December 19, 1921, to January 16, 1922.[16] The borough was named after Sir George Carteret, one of the first proprietors of New Jersey, and his son Philip Carteret, the first royal governor of New Jersey.[17][18]

Rockaway Township was incorporated as a township by an act of the New Jersey Legislature on April 8, 1844, from portions of Hanover Township and Pequannock Township.[21] Portions of the township were taken to form Rockaway Borough (June 19, 1894), Port Oram (June 26, 1895, now Wharton) and Denville Township (April 14, 1913).[22] Portions of the township were annexed to Boonton Township in 1906 and to Rockaway Borough in 1908.[23]

The area that is now Mahwah was originally formed as Hohokus Township on April 9, 1849, from portions of the former Franklin Township (now Wyckoff). While known as Hohokus Township, territory was taken to form Orvil Township (on January 1, 1886; remainder of township is now Waldwick), Allendale (November 10, 1894), Upper Saddle River (November 22, 1894), and Ramsey (March 10, 1908). On November 7, 1944, the area was incorporated by an act of the New Jersey Legislature as the Township of Mahwah, based on the results of a referendum held that day, replacing Hohokus Township.[25] New Jersey Monthly magazine ranked Mahwah as its ninth best place to live in its 2008 rankings of the “Best Places To Live” in New Jersey.[26]

When surveying the area now known as Maplewood, Robert Treat found several trails used by Lenape tribes of Algonquian Native Americans, though there was only sparse pre-European settlement. These paths form the basis for what are the township’s main thoroughfares today.[25]