Which river forms part of the border between West Virginia and Virginia?

The Potomac River is the river that forms part of the border between West Virginia and Virginia. This river has significant historical, geographical, and economic importance in the region. The section of the Potomac River that borders West Virginia and Virginia is not only vital for its natural resources but also acts as a boundary between the two states.

Understanding the geographical layout of the region highlights why the Potomac River is key. It flows through the Appalachian Mountains and creates a natural division between West Virginia and Virginia, with the river's path closely following the state line in certain areas. The river is known for its recreational opportunities and its role in the transportation and trade historically.

In contrast, the Mississippi River is located much farther to the west and does not play a role in the border between these two states. The Ohio River, although important in the context of West Virginia's geography, serves as part of the border with Ohio, not Virginia. The Tidewater River is less well-known and does not have a significant impact on the borders in this area. Thus, recognizing the Potomac River as the correct answer highlights its geographical significance to West Virginia and Virginia.