Penns Grove had the fourth-highest property tax rate in New Jersey, with an equalized rate of 5.556% in 2020, compared to 3.476% in Salem County and a statewide average of 2.279%.[22]

What is now South Bound Brook was originally formed as a town within Franklin Township. On March 16, 1869, the name of the community was changed to Bloomington, which lasted until May 29, 1891, when the name reverted to South Bound Brook town. South Bound Brook was incorporated as an independent borough by an act of the New Jersey Legislature on April 11, 1907, based on the results of a referendum held on May 1, 1907.[21][22]

Flemington is an independent municipality completely surrounded by Raritan Township and is located near the geographic center of the township.

The borough of Spring Lake Heights was formed by an act of the New Jersey Legislature on March 19, 1927, from portions of Wall Township, based on the results of a referendum held on May 3, 1927.[21] The borough was named for Spring Lake, which was named for a clear spring-fed lake.[22][23][24]

Hampton Township was formed from portions of Sussex County by an act of the New Jersey Legislature on April 11, 1864.[18] The township was named for Jonathan Hampton, who donated land in 1769 to the Episcopal Church of Newton.[19] State legislator Robert Hamilton, an Episcopalian, appreciated Hampton’s generosity, and gave the township its name.[20] Portions of the township were taken on February 24, 1904, to form Fredon Township.[18]

Franklin, known as the “Fluorescent Mineral Capital of the World,”[22] is located over a rich ore body containing more than 150 minerals, many of them fluorescent and 25 of which are found nowhere else on earth. Settled in the 17th century, the village known as Franklin Furnace after Benjamin Franklin,[23][24][25] developed near iron mines and iron smelting operations located along the Wallkill River. In the early 19th century, zinc deposits in the area began to be developed commercially. For most of the century many small companies mined zinc and iron in the Franklin area. In 1897 all zinc mining efforts merged into the New Jersey Zinc Company, which was a major controlling factor in the development of Franklin. Immigrants from Russia, Britain, Hungary and Poland joined the work force at the mine. The population, 500 in 1897, had swelled to 3,000 by 1913. On March 18, 1913, the Borough of Franklin was incorporated from portions of Hardyston Township, based on the results of a referendum held on April 23, 1913.[26]

Greenwich Township was first formed on March 1, 1695, and was formally incorporated as one of New Jersey’s initial group of 104 townships by an act of the New Jersey Legislature on February 21, 1798. Over the centuries, portions of the township were taken to form Woolwich Township (March 7, 1767), Franklin Township (January 27, 1820), Spicer Township (March 13, 1844; now Harrison Township), Mantua Township (February 23, 1853), East Greenwich Township (February 10, 1881) and Paulsboro (March 2, 1904).[21] The township was named for Greenwich, England.[22]

The borough is known for the Mendham Historic District, which is listed on the National Register of Historic Places with notable landmarks that include the Phoenix House, which serves as the borough’s municipal building, and the historic Black Horse Inn and Tavern.[22] New Jersey Monthly magazine ranked Mendham Borough as the number one place to live in the state in its 2013 rankings of the “Best Places to Live” in New Jersey.[23]

Demarest was formed by an act of the New Jersey Legislature on April 8, 1903, from portions of Harrington Township and Palisades Township.[21][22] The borough was named for the Demarest family[23] and for the Demarest train station, which had in turn been named for Ralph S. Demarest, who was a director of the Northern Railroad of New Jersey that built the station and represented the area in both the New Jersey General Assembly and the New Jersey Senate in the mid-19th century.[24][25]

Brielle was formed as a borough by an act of the New Jersey Legislature on April 10, 1919, from portions of Wall Township, based on the results of a referendum passed on June 3, 1919.[21] The borough was named for Brielle, a town in the Netherlands.[22]