The Potomac River Flows South—Southeast, Then Northeast to the Chesapeake

The Potomac River's journey is a study in directional nuance. Its overall course is southward—from the Allegheny Mountains of West Virginia to the Chesapeake Bay—but the path it takes is anything but a straight line.

Source to Sea: The Route

The Potomac begins at Fairfax Stone, West Virginia (3,140 ft elevation), where the North and South Branches converge. From there:

• Upper Potomac: Flows northeast, then generally southeast through the Ridge-and-Valley Appalachians, forming the Maryland–West Virginia border.
• Great Falls: Drops 76 feet in less than a mile at Great Falls Park—a dramatic gorge popular with kayakers and hikers.
• Tidal Potomac: Below Little Falls (near D.C.), the river becomes tidal and estuarine, widening dramatically.
• Final stretch: Turns northeast past Alexandria, Mount Vernon, and the Naval Surface Warfare Center, broadening to 11 miles wide at the mouth before entering the Chesapeake Bay at Point Lookout, Maryland.

Why Direction Matters

The Potomac's northward-to-southeast-to-northeast arc reflects the structural grain of the Appalachians—it follows the Great Valley, then cuts across the Fall Line (where hard bedrock meets coastal plain), then widens into a drowned river valley (ria) as sea level rose after the last glaciation.

Historical and Modern Significance

"The Nation's River" flows past the capital, Mount Vernon, and countless Civil War sites. It supplies drinking water to 5 million people (D.C. metro area), supports recreation (fishing, paddling, the annual Nation's Triathlon), and remains a contested resource—nutrient pollution, sediment, and interstate water allocation (Maryland vs. Virginia vs. West Virginia) are managed by the Interstate Commission on the Potomac River Basin.

So: the Potomac flows south in the broad sense—but its meanders tell the geologic and human story of the mid-Atlantic.