The Rio Grande, or big river, has been an integral part of New Mexico’s history for thousands of years. Running through the entire state, it is both its backbone and lifeblood. It originates in the southern Rocky Mountains of Colorado, then forms the boundary between Texas and Mexico before spilling into the Gulf of Mexico. More than 1,800 miles long, it is one of the great rivers of the world. It has provided water for irrigated crops and sustenance to countless peoples who lived and traveled along its banks. Through the Mesilla Valley, the river is now highly channeled and controlled by several dams, the largest of which is Elephant Butte Dam, seventy miles north. As a result, the river no longer changes course or floods as it frequently did in the past.