New Castle is a city in Lawrence County, Pennsylvania, United States, 50 miles (80 km) northwest of Pittsburgh and near the Pennsylvania-Ohio border just 18 miles (29 km) east of Youngstown, Ohio.
In 1798, John Carlysle Stewart, a civil engineer, traveled to western Pennsylvania to resurvey the "donation lands" resurveyed lands, which had been reserved for veterans of the Revolutionary War. He discovered that the original survey had neglected to stake out approximately 50 acres (20 ha) at the confluence of the Shenango River and the Neshannock Creek, at that time a part of Allegheny County. Claiming the land for himself, he laid out what was to become the town of New Castle. Stewart laid out the town of New Castle in April 1798. It comprised approximately that same 50 acres (20 ha), in what was then part of Allegheny County.In 1825, New Castle became a borough, having a population of about 300. The city later became a part of Mercer County. On April 5, 1849, the Governor of the Commonwealth of Pennsylvania signed an act creating Lawrence County named in honor 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 about 6,000.