the ocean that forms the western border of the US is the Pacific Ocean
nothing
The Mississippi River forms the western border of Illinois.
The Uruguay River forms the western border of Uraguay with Argentina.
The Mississippi river forms the western border of the southern colonies.
The Uruguay River forms the western border of Uraguay with Argentina.
The western border of Moldova is formed by the Prut river.
The Mississippi River forms the western border of Illinois.
California's eastern border and Arizona's western border.
The Mississippi River forms the wavy western border of Illinois. And the Ohio Wabash River is the southern border of Illinois.
The pacific ocean.
chile