The Tularosa Basin is a graben basin in the Basin and Range Province and within the Chihuahuan Desert, east of the Rio Grande in southern New Mexico and West Texas, in the Southwestern United States. Geography The Tularosa Basin is located primarily in Otero County. It covers about (35% larger than Connecticut). It lies between the Sacramento Mountains to the east, and the San Andres and Oscura Mountains to the west. The basin stretches about north–south, and at its widest is about east-west. It is geologically considered part of the Rio Grande Rift zone, which widens there due to the slight clockwise rotation of the Colorado Plateau tectonic plate. Notable features of the basin include White Sands National Park, Oliver Lee Memorial State Park, the Carrizozo Malpais lava flow, Holloman Air Force Base, and the White Sands Missile Range with the historic Trinity nuclear test Site. Tularosa Creek flows westward into the Tularosa Basin just north of the village of Tularosa. The distinct northwestern New Mexico Tularosa River is located in Catron County. Hydrologically, the Tularosa Basin is an endorheic basin, as no water flows out of it. The basin is closed to the north by Chupadera Mesa and to the south by the broad flat 4000-foot-elevation plain between the Franklin and Hueco Mountains, with the conventional boundary taken to be the New Mexico–Texas border. Surface water that does not evaporate or soak into the ground eventually accumulates at playas (intermittently dry lake beds), the largest of which is Lake Lucero, at 3888 feet elevation, at the southwest end of the White Sands dunes. The White Sands are a 710-km2 (275-mi2) field of white sand dunes composed of gypsum crystals. To the north of Lake Lucero are extensive alkali flats, which produce additional gypsum for wind deposition on the dunes. History Apache, Spanish, and U.S. 'Old West' When the Spanish arrived in the Tularosa Basin, they found springs and small streams coming from the Sacramento Mountains that fed a relatively lush grassland on the eastern side of the basin. While the Spanish tried some sheep ranching and some mining, the area remained firmly under Apache control until the 1850s, when the United States established its military presence at Fort Stanton (in the Sacramento Mountains) (1855–1896), Torreon Fort (near Lincoln) (1850s), and Camp Comfort (1858–1859) at White Sands. Under US military protection, the first permanent settlement was established in 1862, when