San Luis Valley

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 (21,000 km²) and sitting at an average elevation of 7,500 feet (2,300 m) 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.

The Sangre de Cristo Mountains form the eastern border of the valley. Blanca Peak is prominent at the southern end of the northernmost section of the mountains, which is known as the Sangre de Cristo Range. There are several passes, with elevations between 9,000 and 10,000 feet (2,700 and 3,000 m), giving access to the valley. La Veta pass, through the Sangre de Cristo Mountains, is used by US Highway 160 and by the San Luis and Rio Grande Railroad tracks.

The Great Sand Dunes is a famous feature of the valley. It lies directly to the west of the Sangre de Cristo Mountains. The dunes can reach 750 feet (230 m) high. The Great Sands Dunes National Park and Preserve is now in place to protect both the dunes and the numerous archeological sites found in the area. The natural valley aquifer is close to the surface in this part of the valley, and helps with maintenance of water levels in the San Luis Lakes, just to the west of the sand dunes.

The San Luis Valley was long part of the lands of the numerous and powerful Ute Indians. The Valley was the first portion of Colorado to be settled by people of European descent. The area was administered as part of the Spanish, later Mexican, province of Nuevo Mexico until the area was purchased by the United States as part of the Treaty of Guadalupe Hidalgo in 1848. Extensive settlement began in the Valley, again primarily by Spanish farmers and ranchers from New Mexico in the 1800s. The history of the post-war U.S. military presence in the Valley is preserved at Fort Garland and other sites in the Valley, which became part of the Territory of Colorado in 1861.