New Castle is a city in and the county chair of Lawrence County, Pennsylvania, United States. It is 50 miles (80 km) northwest of Pittsburgh close the Pennsylvania–Ohio border, approximately 18 miles (29 km) southeast of Youngstown, Ohio. As of the 2020 U.S. census, the city had a population of 21,926. It is the commercial middle of a fruitful agricultural region,
officially the New Castle micropolitan area, which had a population of 86,070 in 2020. New Castle furthermore anchors the northwestern allowance of the Pittsburgh–New Castle–Weirton entire sum statistical 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 native survey had neglected to stake out nearly 50 acres (20 ha) at the confluence of the Shenango River and Neshannock Creek, at that period a allocation 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 1798 what was to become the town of New Castle. It comprised nearly that similar 50 acres (20 ha), in what was later part of Allegheny County.

In 1825, New Castle became a borough, having a population of approximately 300. The city complex became a allowance of Mercer County. On April 5, 1849, the manager of Pennsylvania signed an prosecution creating Lawrence County, named in tribute of U.S. Navy Captain James Lawrence. New Castle became a city in 1869 and was headed by its first mayor, Thomas B. Morgan. At that time, the population had increased to practically 6,000.

In 1849, a activity of Old Order Amish families from Mifflin County, Pennsylvania, settled just north of New Castle in New Wilmington. Later migrations from Holmes County, Ohio, would make this Amish community one of the largest in Pennsylvania. Approximately 2,000 Amish stimulate and doing presently in the townships north of New Castle.