The Potomac River flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States (USA). The river is approximately 413 statute miles (665 km) long, with a drainage area of about 14,700 square miles (38,000 km²). In terms of area, this makes the Potomac River the fourth largest river along the Atlantic coast of the USA and the 21st largest in the USA. Over 5 million people live within the Potomac watershed, where precipitation provides the equivalent of over 8 m³ (more than 2,100 US gallons) of water per person per year.

The Tidal Basin is a partially man-made inlet adjacent to the Potomac River in Washington, D.C. It is part of West Potomac Park and is surrounded by the Jefferson Memorial and the Franklin Delano Roosevelt Memorial. The basin covers an area of about 107 acres and is 10 feet deep. The concept of the Tidal Basin originated in the 1880’s to serve both as a visual centerpiece and as a means for flushing the Washington Channel, a harbor separated from the Potomac River by fill lands where East Potomac Park is situated.