In most cases the eastern boundary of something will touch the western boundary of the next door something. Where "something" can be a state, province, country, estate, ocean, lake river, Earth plate etc.
A divergent boundary.
Spain is the only country to border Portugal to the east.
The eastern boundary of Massachusetts is defined by the Atlantic Ocean.
The Ural Mountains form the western boundary for the continent of Asia.
There was one major geographic feature that formed the Western boundary of the 13 colonies. This boundary feature was the Appalachian Mountains.
Spain forms the eastern boundary of Portugal.
The southern half of the eastern boundary of Alabama is the Chattahoochee River.
Eastern U.S.A.
A divergent boundary.
The Indian Ocean forms the eastern boundary of Africa.
they were the Oregon and spanish
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.
Atlantic ocean
The Atlantic Ocean.
The eastern boundary was the Mississippi River, while the western boundary was the original 13 colonies along the Atlantic coast.
The eastern boundary of ancient Egypt was typically the Red Sea, although it varied at times. The western boundary was the Western Desert. The northern boundary was the Mediterranean Sea.