savannah
Georgia's eastern border is the Atlantic Ocean
South Carolina and the Atlantic Ocean border the eastern side of Georgia. The Savannah River forms the border between Georgia and South Carolina.
based on the exact wording of the question most likely the alazani river but possibly also the Savannah tugaloo chatooga river which tho it has 3 different names is really all one river & forms all of the eastern border of the other Georgia
The Snake River forms part of Oregon's eastern border
The river that forms part of Alabama's eastern border is the Chattahoochee River. It flows southward and serves as a natural boundary between Alabama and Georgia. The river is significant for both its ecological importance and its role in regional water supply.
The Connecticut River forms the eastern border of Vermont. The river is 410 miles long and is the longest river in New England.
The Mississippi River forms most of Arkansas's eastern border.
Mississippi River
The Mississippi River forms most of Arkansas's eastern border.Mississippi River
The Chattahoochee River forms Georgias's southwestern border.
Ohio River
The Mississippi River forms most of Arkansas's eastern border.Mississippi River