National Park estab. 1944, 250 mi. SE of El Paso along the Rio Grande, comprising 801,000 acres. Named a U.S Biosphere Reserve in 1976, and the largest protected area of the Chihuahuan Desert. Home of the Chisos Mts. and the Santa Elena Canyon. Human artifacts date back 10,500 yrs. Exceptionally remote. Many wild areas. Sparse development.