The San Luis Valley is an extensive alpine valley in the United States states of Colorado and New Mexico covering approximately 8,000 square miles and sitting at an average elevation of 7500 feet above sea level. The valley sits atop the Rio Grande Rift and is drained to the south by the Rio Grande River, which rises in the San Juan Mountains to the west of the valley and flows south into New Mexico. The valley is approximately 122 miles (196 km) long and 74 miles (119 km) wide, extending from the Continental Divide on the northwest rim into New Mexico on the south.