South New Castle is a borough in Lawrence County, Pennsylvania. It surrounds the nearby city of New Castle.

According to the United States Census Bureau of 2000, South New Castle is home to more than 800 residents. The borough has a total area of 0.3 square miles.

The racial composition of South New Castle is predominately white, with more than 99% of the population.

South New Castle has a few hundred households. The median income for a household in the borough is $30,568, and the median income for a family is $38,472.

Lawrence County is surrounded by three counties in Pennsylvania and two counties of Ohio. The county has a population of about 100,000 people living in an area of 363 square miles.

Lawrence County has ten boroughs, sixteen townships and three unincorporated communities The county seat is New Castle, the county’s only city.

Lawrence County is served by nine public school districts.