Blanca Peak (Navajo: Sis Naajinį́) is the fourth highest summit of the Rocky Mountains of North America and the U.S. state of Colorado. The ultra-prominent 14,351-foot (4,374 m) peak is the highest summit of the Sierra Blanca Massif, the Sangre de Cristo Range, and the Sangre de Cristo Mountains. The fourteener is located 9.6 miles (15.5 km) north by east (bearing 9°) of the Town of Blanca, on the drainage divide separating Rio Grande National Forest and Alamosa County from the Sangre de Cristo Land Grant and Costilla County. The summit is the highest point of both counties and the entire drainage basin of the Rio Grande. Below the steep North Face of Blanca Peak two live Glaciers once developed, until extinction sometime after 1903. North & South Blanca Glaciers were located at 37° 35N.,longitude 105° 28W. Blanca Peak is higher than any point in the United States east of its longitude.

The Blanca Peak Tripoint of Alamosa, Costilla, and Huerfano counties is located on the same drainage divide approximately 251 feet (77 m) northeast by north (bearing 30°) of the Blanca Peak summit at the boundary of the San Isabel National Forest. The Blanca Peak Tripoint is the highest point in Huerfano County.