It's one of the longest rivers in South America. The name of it is the Orinoco River. It flows all the way to the Atlantic Ocean.
Colombia
The Arauca River is a South America river in Colombia and Venezuela. The Atabapo River forms the international boundary between Venezuela and Colombia. The Amacuro River forms part of international boundary between Venezuela and Guyana.
Brazil
amazon river?
From what I know, it is not a river that forms much of the border. It is the Bitterroot mountain range.
Golf of Mexico
The Limpopo forms that border between Zimbabwe and South Africa.
The Colorado River forms the border between Arizona and California
The Limpopo forms that border between Zimbabwe and South Africa.
The border between Mississippi on the west and Arkansas on the east is the Mississippi River. It also forms the border between Arkansas and Tennessee.
the river that forms the border between India and Kentucky is the Mississippi River.
The Missouri River forms the border between Iowa and Nebraska.