The Pecos River is a river that runs through the state of New Mexico in the United States. It is approximately 926 miles long and is the longest river in the state. The river originates in the Sangre de Cristo Mountains in northern New Mexico and flows southeastward, eventually emptying into the Rio Grande near the city of Del Rio, Texas. Along its course, it passes through several cities, including Santa Fe, Carlsbad, and Roswell. The Pecos River is an important source of water for the region and is used for irrigation, recreation, and other purposes.