New Castle is a city in and the county seat of Lawrence County, Pennsylvania, United States. Located along the Shenango River at the mouth of Neshannock Creek, it is northwest of Pittsburgh near the Pennsylvania–Ohio border, approximately southeast of Youngstown, Ohio. As of the 2020 census, the city had a population of 21,926. The commercial center of a fertile agricultural region, New Castle is included in the northwestern part of the Pittsburgh metropolitan area.
In 1798, John Carlysle Stewart, a civil engineer, traveled to western Pennsylvania to resurvey the "donation lands", which had been reserved for veterans of the Revolutionary War. He discovered that the original survey had neglected to stake out approximately at the confluence of the Shenango River and Neshannock Creek, at that time a part of Allegheny County. The Indian town of Kuskusky was listed on early maps in this location. Claiming the land for himself, he laid out in April