Pacific Ocean
Quebec, Canada
It is the Canda-United States border, but is officially known as the International Border.
Minnesota only forms a border for one country: Canada.
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.
Canada forms the most northerly border of the U.S.