Sierra County administrative offices are located at 855 Van Patten Street, Truth or Consequences, NM 87901; phone: 575-894-6215.
Human occupation in the area began in the Paleoindian period of 10,000 to 6,000 B.C. Mammoth and bison fossils found along the shores of Elephant Butte Lake show that paleoindian cultures hunted those species. Archaic period (6,000 B.C.—200 A.D.) hunters and gatherers also left behind evidence of their presence. Between 200 and 1400 (The Formative Period) the Mimbres, Jornada Mogollon, and Rio Grande pueblo groups thrived, and specialized in pithouse settlements, and later pueblo villages, as well as dry-land farming.
Sierra County historically was populated by several bands of Apaches, whose presence dates from the 14th and 15th centuries. The Mescalero Apache inhabited the region east of the Rio Grande and the Chiricauhua Apache inhabited the region to the west. The cultural penchant of Apaches for raiding slowed Hispanic and Anglo settlement in the area for a long time. Spanish forays into the region began in the 1500s and substantial trade routes, including the Camino Real, were established.
Permanent European settlement dates from the 1840s, supported by the presence of military forts, and from the earliest times, agriculture and mining were the main forms of livelihood. Although some settlement of the County occurred from the El Paso area, the predominant pattern was from the long time Spanish settlements in the northern part of the State, names like Apodaca, Armijo, Baca, Torres, and Montoya. Sierra County was the southern limit of the distinctive culture of northern New Mexico.
Sierra County was formed in 1884 from Socorro, Dona Ana, and Grant Counties. During the late 19th and early 20th centuries, the U.S. government determined that water along the Rio Grande could be better distributed through a series of water control projects. The Bureau of Reclamation, began in 1902, by 1911 was building the Elephant Butte Dam.
The official name for the City of Truth or Consequences between 1916, when the town was incorporated) and 1950 was Hot Springs because of their importance in stimulating an early visitor economy in the area. Recreational facilities were first constructed at Elephant Butte Reservoir in the late 1930s.