• Texas is bordered by three rivers.texas map image by Vladislav Gajic from Fotolia.com
  
  Many states in the United States have borders, or partial borders, formed along the natural lines of rivers. Three rivers separate Texas from its neighbors almost completely. Only New Mexico is divided from Texas by the straight map line typical of western states. Eastern Texas is partially separated from Louisiana by the Sabine River. The Red River creates most of the northern border of Texas, separating it from Oklahoma. The international border between Texas and Mexico is the Rio Grande.
  
  

Sabine River

• The Sabine River provides a partial eastern border between Texas and Louisiana as established in the Adams-Onis Treaty of 1819. This river forms from several small streams and formally becomes the Sabine River where the Caddo Fork meets the South Fork. Flanked on both sides by Cypress trees, the Sabine River gets its name from the Spanish word "sabinas" meaning "cypress." Flowing 555 miles, the Sabine River empties into the Sabine Lake and eventually is drained into the Gulf of Mexico. Located entirely in an area of heavy rainfall, the areas around this river are prone to periodic flooding.
  
  

Red River

• The Red River creates a partial northern border between Texas and Oklahoma. The river originates in the Texas Panhandle, meanders through Arkansas into Louisiana, and finally empties in the Mississippi River. The Red River gets its name from the red-clay farms it waters in Texas, which turn the water red during flood periods. The Denison Dam on the Red River, completed in 1943, creates Lake Texoma, one of the largest lakes in the United States. The river was established as the northern and eastern border of Spanish Texas in 1805, and again in 1819 in the Adams-Onis Treaty.
  
  

Rio Grande River

• Called Rio Bravo in Mexico, the Rio Grande has separated Texas from Mexico since the Treaty of Guadalupe Hidalgo in 1848. It is the 22nd longest river in the world at 1,896 miles. This river begins in the San Juan Mountains of Colorado, travels through New Mexico, and empties into the Gulf of Mexico. Creating an international border with a body of water has distinctive challenges. The Rio Grande is constantly moving, changing and forming new channels. This movement obscures the exact boarder and makes it difficult to define.