article: Mason–Dixon line
links: Slave and free states William Penn Atlantic Ocean British government England American Civil War 40th parallel north James I of England Scots-Irish English law Surveying Pennsylvania Potomac River Charles II of England Chesapeake Bay Catholic Sheriff Ohio Northern United States English people Latin Ireland GPS Southern United States Colonist Newfoundland Charles I of England Latitude Virginia Colony Cecilius Calvert, 2nd Baron Baltimore Philadelphia Resignation Lancaster County, Pennsylvania Susquehanna River Mississippi River Degree (angle) Maryland Ohio River Religious Society of Friends Secretary of State