The country is Eritrea, and it's eastern boundary is formed by the Red Sea.
Sudan is the most eastern country to Eritrea.
Spain forms the eastern boundary of Portugal.
The Indian Ocean forms the eastern boundary of Africa.
The southern half of the eastern boundary of Alabama is the Chattahoochee River.
Spain is the only country to border Portugal to the east.
Minnesota.
The Atlanic Ocean
Mississippi
The Connecticut River
Mississippi
The Mississippi River is the East boundary for Arkansas.