Eastern U.S.A.
The Atlantic ocean.
Spain forms the eastern boundary of Portugal.
The southern half of the eastern boundary of Alabama is the Chattahoochee River.
A divergent boundary.
The Indian Ocean forms the eastern boundary of Africa.
they were the Oregon and spanish
Russia does not share an eastern border with anyone, but it is on the coast of the Bering Sea and just across that is the US state of Alaska.
The country is Eritrea, and it's eastern boundary is formed by the Red Sea.
Spain is the only country to border Portugal to the east.
The Atlantic Ocean.
The eastern boundary was the Mississippi River, while the western boundary was the original 13 colonies along the Atlantic coast.