caucausus mountains
The Ural Mountains.
A physical feature that forms part of the border of New York State is Lake Ontario. If you mean the border around New York City, a physical feature would be the Hudson River.
The Mississippi River forms Arkansas' eastern border.
The physical feature that forms Uruguay's western boundary with Argentina is the Uruguay River. It also forms part of the Brazilian-Argentine border.
Mexico
The Mississippi river
The Rio Grande river, also known as Rio Bravo in Mexico.
A River
Mississippi river
The Ural Mountains
There is no geographical feature that forms the border between Portugal and Spain. The Strait of Gibraltar and Mediterranean Sea separates Iberian Spain and Morocco. The Pyrenees Mountains forms the border between Spain and France and Spain and Andorra.
The Ural Mountains
The Ural Mountains