Rio Grande

At about 1,885 miles in length, the Rio Grande is America's fourth longes river. It rises in the mountains of south central Colorado and flows south through New Mexico. It then flows east, where it forms the entirety of the border between Texas and Mexico before flowing out into the Gulf of Mexico. Because much of the river's water is diverted for agriculture and dams, only about 20% of its natural discharge reaches the Gulf of Mexico.