It enters Elephant Butte Reservoir, the largest water body in New Mexico, between Bosque del Apache National Wildlife Refuge and the city of Truth or Consequences.

[6] Before the Ancestral Rio Grande was integrated into a single watercourse, the valley was a series of closed bolsons each draining into a central playa.

[8] Although the Rio Grande flows primarily through desert and arid lands, the valley floor nearest the river supports a rich bosque habitat, featuring large cottonwood gallery forests.

Artifacts left behind by the Folsom culture include flakes of stone cherts from the Chuska Mountains, the Zuni Mountains, and the Rio Puerco Escarpment, suggesting they were moving east toward the Rio Grande, collecting high-quality stones along the way, and stopping to camp and kill game upon the mesa, before continuing west and south across the Americas.

[9] The Ancestral Puebloans inhabited the valley year-around starting sometime before 1300 CE, after abandoning their settlements near the Four Corners region, probably due to drought, in the late Pueblo III Period.

They traded with the Pueblos their bison meat, hides, and stone tool materials for Puebloan maize and woven cotton goods.

Since the early 21st century, substantial progress has been made in dating and distinguishing their dwellings and other forms of material culture.

[12][13] In the autumn of 1540, a military expedition of the Viceroyalty of New Spain led by Francisco Vásquez de Coronado, Governor of Nueva Galicia, reached the Tiwa pueblos in the valley around the future site of the Albuquerque Metro.

The road first entered the valley at El Paso del Norte (present day Ciudad Juárez, Chihuahua).

North of Las Cruces, New Mexico, the road left the valley and traversed the Jornada del Muerto Desert.

[17] La Villa de Alburquerque was founded by Nuevo México governor Francisco Cuervo y Valdés in 1706.

Flooding resulted from seasonal meltwater from snow in the northern mountains in the spring, and from storm runoff during the New Mexican Monsoon in the summer.

[19] The Spanish noted that Pueblos living along the river would often build on raised land or natural highpoints along the valley floor; rarely, they would abandon settlements if the flooding was too frequent or severe in a particular location.

Records indicate that the entire valley was flooded from Albuquerque to El Paso, which caused the river to shift to new channels in several locations.

[23] U.S. Route 85, part of the Pan-American Highway, was constructed along the length of the valley from El Paso, Texas to then-US 66 (now NM 6) in Los Lunas.

Repeated floods in the middle Rio Grande Valley have created some of the most fertile agricultural lands in the Southwest.

Livestock includes cattle, dairy, sheep, angora goats, pigs, chickens, turkeys, and honey bees.