10 Remarkable Facts About the Potomac River

The Potomac River is a historical waterway on the eastern shore of Virginia. It runs through five different states, reaches a maximum depth of 107 feet, and even has sharks swimming in its waters. There are more remarkable facts about the Potomac River to discover, so let’s go!

1. The River Starts in a West Virginia State Park

Before we get too deep, we need to start from the beginning. Where does the Potomac River start?

West Virginia’s Fairfax Stone Historical Monument State Park is where the river begins. Following its journey east, it winds its way through mountains, meets with other rivers, tumbles over waterfalls, and finally flows into the Chesapeake Bay at Point Lookout in Maryland.

2. At the Deepest Point, the River Reaches Depths of 107 Feet

At 405 miles long, the Potomac River has an average depth of 24 feet. However, the deepest point of the Potomac River is 107 feet deep! As impressive as that seems, the Hudson River — the deepest river in the U.S. — reaches a dizzying depth of 216 feet.

3. The Potomac River Is Over Two Million Years Old

Over 2 million years ago, the Potomac River as we know it formed as a result of erosion as the water cut through the mountains. Fluctuating sea levels affect the depth of the water, which is why the river has both deep and shallow areas.

4. The River Was Used by Troops and Slaves During the Civil War

You might wonder what’s so famous about the Potomac River. During the Civil War, both U.S. troops and slaves encountered the mighty river. However, one side saw it as a challenge and the other as a corridor.

While Union and Confederate troops saw the river as an obstacle to cross on their way into battle, slaves escaping to freedom through the Underground Railroad found that the Potomac was deep enough for a small boat to cross and shallow enough to walk, ride, or drive a wagon through.

5. You Can Find Dolphins and Sharks in the Potomac River

Are you surprised by the fact that there are dolphins in the Potomac River? Between July 2015 and October 2018, the Potomac-Chesapeake Dolphin Project reported over 250 mothers and almost 300 calves.

Well, sharks live there too! Sandbar, sand tiger, smooth dogfish, and bull sharks all congregate at the mouth of the river.

6. Celebrities Have Tested the River’s Waters

Since 1971, it has been illegal to swim in the waters of Potomac between Great Falls and the southern Maryland/DC line. That’s because it’s alleged to have unsafe levels of contamination and dangerous undercurrents. However, DC residents are quick to point out that other rivers with similar cleanliness levels are legal to swim in.

Finally, in 2022, the tides began to shift. The House passed HR 7776 as a way to appease the community, which has pushed to lift the decades-long ban.

So no, you still can’t legally swim in the DC section of the Potomac River. But according to musician Lorde, you can… just don’t let the authorities catch you!

7. The Potomac River Supplies 6.11 Million People Within Its Watershed

Why is the Potomac River important? Well, the fact is that the Potomac River covers almost 15,000 square miles and supplies water to 6.11 million people. The health of the basin equates to the health of millions of residents, which is why restoration and conservation efforts are in place today.

8. The River Spans Across Five U.S. States

The longest river in the U.S. is the Mississippi, which runs through 10 states. Meanwhile, the Potomac River spans across five — West Virginia, Virginia, Maryland, Pennsylvania, and the District of Columbia.

9. There Are Many Ways to Cross the Potomac River

At 383 miles long, there are plenty of bridge crossings over the Potomac. Some of the most popular are the:

• Harry W. Nice Memorial Bridge
• American Legion Memorial Bridge
• Woodrow Wilson Memorial Bridge
• Arlington Memorial Bridge
• Theodore Roosevelt Bridge
• Francis Scott Key Memorial Bridge
• Chain Bridge
• B&O Railroad Bridge

10. The Potomac Is a Freshwater River

The Potomac is a freshwater river, but it converges with the brackish waters — which contain more salinity than freshwater, but not as much as salty seawater — of the Chesapeake Bay in the Potomac Estuary.

This is why you see the types of sharks that can live in low salinity conditions swimming in the Potomac!

Recap of Remarkable Facts About the Potomac River

Bet you never knew a river could be so fascinating! To conclude, let’s summarize what you just learned.

The photo featured at the top of this post is © Jon Bilous/Shutterstock.com