| St. Marys River | |
|---|---|
.jpg) A landscape image of the St. Marys River | |
| Location | |
| Country | United States |
| State | Maryland |
| County | St. Mary's County |
| Physical characteristics | |
| Mouth | |
• location | Potomac River |
• elevation | 0 feet (0 m) |
| Length | 22.3 miles (35.9 km) |
The St. Marys River (sometimes spelled St. Mary's River) is a 22.3-mile-long (35.9 km)[1] river in southern Maryland in the United States. It rises in southern St. Mary's County, and flows to the southeast through Great Mills, widening into a tidal estuary near St. Mary's City, approximately 2 miles (3 km) wide at its mouth on the north bank of the Potomac River, near the Chesapeake Bay to the east.