Colorado Desert The Colorado Desert is a large arid depression in the southeastern part of the U.S. state of California and the northeastern portion of the Mexican state of Baja California. It encompasses approximately 2,500 sq mi (40,000 kmē) east of Los Angeles and San Diego, extending from the San Bernardino Mountains east and southeast to the Colorado River, from which it takes its name. The region is essentially the northwest extension of the Sonoran Desert to the southeast. The region includes the heavily-irrigated Coachella and Imperial valleys on the north and south side of the Salton Sea respectively. It is crossed by several mountain ranges, including the San Jacinto, Santa Rosa, Little San Bernardino, and Chocolate mountains. Joshua Tree National Park is located on the northern edge of the region and includes many of the unique species and habitats of the region. Santa Rosa and San Jacinto National Monument, created in 2000, encompasses much of the San Jacinto and Santa Rosa mountains along the western side of the region. Anza-Borrego Desert State Park, the largest state park in the contiguous United States, covers 600,000 acres (2400 kmē) from the edge of the coastal mountains east of San Diego to the Salton Sea and south almost to the US-Mexico border. From Wikipedia, the free encyclopedia