The Potomac River is near Antietam, flowing approximately 10 miles to the east of the battlefield.

This significant waterway played a crucial role during the Civil War, serving as a strategic boundary between the Union and Confederate territories. The river's proximity influenced troop movements and logistics for both sides, particularly during the Battle of Antietam on September 17, 1862. The Potomac also provided a natural barrier that affected military strategies and engagements throughout the war. Today, the river remains an important historical landmark, reflecting the geographical context of key Civil War battles in the region.