The Patapsco Valley is a small valley surrounding the Patapsco River in central Maryland. The region is known for its historical significance as a major economic and industrial center in the eighteenth and nineteenth centuries.

The Patapsco River mainstem is a 39-mile (63 km) river in central Maryland that flows into the Chesapeake Bay. The river's tidal portion forms the harbor for the city of Baltimore. With its South Branch, the Patapsco forms the northern border of Howard County, Maryland. The name "Patapsco" is derived from the Algonquian pota-psk-ut, which translates to "backwater" or "tide covered with froth".