Joppa is a former town and current planning region of Harford County, Maryland. Joppa was founded as a British colonial settlement on the Gunpowder River in the early 18th century and designated as the first county seat of the large Baltimore County. The original boundaries of Baltimore County were defined in 1659 in northeast Maryland, with a larger territory than the current one. The settlement was named for the Biblical town of Joppa in the ancient Holy Land. (This area is now known as Jaffa, Israel.) After the county seat was moved to the port city of Baltimore in 1768, businesses followed, and Joppa declined.