Potomac River

The Potomac River is a major waterway in the Mid-Atlantic region of the United States.

It is the fourth-largest river along the East Coast. The river drains a massive area known as a watershed. More than 6 million people live within this watershed. The river serves as a natural border for several locations. It separates Maryland from Washington, D.C. on the left descending bank. It also forms the border between West Virginia and Virginia on the right descending bank.

The river begins at two distinct sources. The North Branch starts at the Fairfax Stone in West Virginia. This location sits at the junction of Grant, Tucker, and Preston counties. The North Branch flows to Jennings Randolph Lake, which is a man-made impoundment. This lake helps with flood control and emergency water supply. The South Branch starts near Hightown in Highland County, Virginia. It begins on the eastern side of Lantz Mountain. This mountain stands 3,934 feet tall. The two branches eventually meet just east of Green Spring, West Virginia.

As the water flows, it moves through five different geological provinces. These are specific types of land formations. The river travels through the Appalachian Plateau and the Ridge and Valley. It also passes through the Blue Ridge and the Piedmont Plateau. Finally, it reaches the Atlantic coastal plain. The river has a stream gradient of 0.14%. This means the water drops 930 meters over a distance of 652 kilometers. At Little Falls, the river reaches the Atlantic Seaboard fall line. This is where the river drops from the Piedmont to the Coastal Plain.

Below the fall line, the river becomes a tidal river. This means the tides of the ocean influence the water. This tidal section is 108 miles long. It stretches from the Washington, D.C. area to the Chesapeake Bay. In this estuary, the water becomes more salty as it moves downstream. The river also grows much wider in this section. At its mouth, the river can reach 11 statute miles in width. This mouth sits between Point Lookout, Maryland, and Smith Point, Virginia.

Human history is deeply tied to these waters. Native Americans lived along the banks for a very long time. The name "Potomac" is a European spelling of Patawomeck. This was the name of an Algonquian village on the southern bank. Native groups had different names for various parts of the river. They called the area above Great Falls "Cohongarooton," meaning "honking geese." Below the falls, they called it "Patawomke," meaning "river of swans." Captain John Smith explored the river in 1608.

The river also played a major role in American politics and war. Washington, D.C., the nation's capital, is located on its banks. Mount Vernon, the home of George Washington, is also located here. During the American Civil War, the river was a boundary. It separated the Union from the Confederacy. The Union's largest army was even named the Army of the Potomac. Today, the river is a place for recreation. In 2006, parts were named a National Recreation Trail. In 2019, a portion became the Mallows Bay–Potomac River National Marine Sanctuary.

The Potomac is part of a much larger environmental system. It connects the mountains of West Virginia to the Chesapeake Bay. Many different streams and rivers flow into it. The Shenandoah River is one major tributary. Many smaller creeks also join the river as it flows toward the sea. This complex network of water supports many different species. Protecting the river helps protect the entire region.