Penns Grove is a borough in Salem County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 5,147, reflecting an increase of 261 (+5.3%) from the 4,886 counted in the 2000 Census, which had in turn declined by 342 (-6.5%) from the 5,228 counted in the 1990 Census.
The area was long primarily agricultural. Penns Grove was incorporated as a borough by an act of the New Jersey Legislature on March 8, 1894, from portions of Upper Penns Neck Township (now Carneys Point Township), based on the results of a referendum held two days earlier. It began to industrialize around this time. The borough's name comes from William Penn.
In the early 20th century, many Italian immigrants from Valle San Giovanni and the surrounding southern province of Teramo came to work at the local E.I. DuPont de Nemours plant in Carneys Point. Many settled on Pitman Street in Penns Grove. In 1925, the Italian community arranged to commission a copy of the statue of the Madonna and Child from the Chiesa della Madonna delle Grazie in Teramo, and had it installed in the Saint James Roman Catholic Church in Penns Grove. Other immigrants from eastern Europe also settled in the county, markedly increasing the population.
Also in the 20th century, the area became a destination for Black Americans in the Great Migration who came north for industrial jobs. Some Black Americans in the area were descended from slave families from the colonial and early federal period.