Bing found the following results
Potomac River - Wikipedia
Potomac, Maryland - Wikipedia
Potomac River | Maryland, Virginia, Washington DC, & Map
A Guide to the Potomac River - Washingtonian
Potomac River - American Rivers
Potomac River - WorldAtlas
THE 15 BEST Things to Do in Potomac - Tripadvisor
History & Culture - Potomac Heritage National Scenic Trail (U.S ...
RiverExplorer - Potomac River Guide
101 River Facts — Potomac Conservancy