The Port Tobacco River is a tidal tributary of the Potomac River located in Charles County, Maryland in the United States. The river is approximately 4.2 miles (6.8 km) in length. Port Tobacco, the county seat of Charles County from 1658 to 1895, was an active port until that portion of the river became silted and unnavigable. When the railroad bypassed the town, business declined, and the county seat was moved to La Plata, Maryland.
- ^ U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed August 15, 2011
Coordinates: 38°27′28″N 77°2′6″W / 38.45778°N 77.03500°W