York County, Pennsylvania, is located in the south-central region of the state. It borders the Susquehanna River to the east and northeast, Maryland to the south, and is generally hilly, rising to the Blue Ridge Mountains in the northwest. The county was created in 1749 from part of Lancaster County. The county seat is the city of York, which lies approximately at latitude 39.92°N and longitude 76.73°W. York County is part of the York-Hanover metropolitan area and lies within the Susquehanna Valley region of Pennsylvania. Geographically, it is surrounded by Cumberland County to the north, Dauphin County to the northeast, Lancaster County to the east, and the Maryland counties of Harford, Baltimore, and Carroll to the south and southwest. The Mason-Dixon line marks its southern border with Maryland. This county is roughly 911 square miles in size, mostly land with some water bodies nearby, and lies within the U.S. Piedmont region.