im pretty sure its the potomac river...
The Potomac River divides Maryland and Virginia (The Southern Border) , but Virginia does not own half of the Potomac River.
Potomac
The Ohio River divides Indiana and Kentucky.
It is Orinoco River
ural river
The Connecticut river
river thames
The Sabine river divides Texas and Louisiana. It was described as the line between the Old South and the new Southwest.
~Ohio River~
Ohio river
Columbia river
Missouri River