I think that it's the Rio Grande, but I'm not positive.
On the US side it is called "Rio Grande"; on the Mexican side it is called "Rio Bravo del Norte".
Rio Bravo
Rio Grande!
The parts of the border that are not in the Rio Grande or the Colorado River are marked by a series of monuments.
The river that flows from the Texas panhandle by the border of Louisiana is the "Red River." There is also a river in the northwestern states also called the "Red River," but don't get confused.
The Great State of Texas.
Type your answer here... texas
The Colorado River forms the border between Arizona and California and between Arizona and Nevada.
Naakáí dinéʼiʼ "Person from Mexico" Naakáí means Mexico. The marks above the vowels are high tone marks. The mark between the e and i is a consonant called a glottal stop.
Iguazu Falls marks the border between Brazil and Argentina.
The Huang He River marks the eastern border of China's Shensi province. The Danube River helps form the border between Romania and Bulgaria.
Texas has 3 landmarks
In "The Lion, the Witch, and the Wardrobe," the border between Narnia and the outside world is marked by the lamp-post in the forest. Exiting through the wardrobe takes you back to the outside world.
The Manchurian Plain marks the northeastern part and the North China Plain marks the east and southeast border.