Eastern Boundary:
* The Sabine River: Forms the border with Louisiana for a significant portion.
Southern Boundary:
* The Rio Grande: Forms the border with Mexico, stretching from El Paso to the Gulf of Mexico.
Western Boundary:
* The Red River: Forms the border with Oklahoma for a large portion. However, the boundary with New Mexico is defined by a combination of rivers, including:
* The Pecos River: Forms a portion of the western border, flowing south toward the Rio Grande.
* The Canadian River: Forms a small portion of the border with New Mexico.
Other Important Rivers:
While not directly boundary rivers, these play a significant role in Texas geography:
* The Brazos River: The longest river in Texas, it flows through the state's central region.
* The Colorado River: Runs through central Texas and empties into the Gulf of Mexico.
* The Trinity River: Flows through the Dallas-Fort Worth area and empties into Galveston Bay.
It's important to note that the specific points where these rivers form the state boundary can be complex due to historical agreements and land surveys.
