The San Luis Valley is the large, generally flat, high mountain valley at the headwaters of the Rio Grande in south central Colorado and far north central New Mexico.
The San Luis Valley is a region in south-central Colorado with a small portion overlapping into New Mexico.
The valley is approximately 122 miles (196 km) long and 74 miles (119 km) wide.
It is an extensive high-elevation depositional basin of approximately 8,000 square miles (21,000 km2) with an average elevation of 7,664 feet (2,336 m) above sea level.
The San Luis Valley contains 6 counties and portions of 3 others.