File:Rio Grande River Valley North of Santa Fe, New Mexico (101307243).jpg

The Rio Grande is a river that flows from south central Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico–United States border. According to the International Boundary and Water Commission, its total length was 1,896 miles (3,051 km) in the late 1980s, though course shifts occasionally result in length changes. Depending on how it is measured, the Rio Grande is the fourth or fifth longest river system in North America.[2] The river serves as a natural border between the U.S. state of Texas and the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas. A very short stretch of the river serves as the boundary between the U.S. states of Texas and New Mexico. Since the mid–20th century, heavy water consumption of farms and cities along with many large hydroelectric dams on the river has left only 20% of its natural discharge to flow to the Gulf. Near the river's mouth, the heavily irrigated Rio Grande Valley is an important agricultural region. The Rio Grande is one of 19 Great Waters recognized by America's Great Waters Coalition.[6]