Sierra County, New Mexico

Sierra County is a county in New Mexico, United States, about 150 miles south of Albuquerque
along the Rio Grande. It had a population of 11,576 at the 2020 census, an estimated 11,500 by
2024, and covers 4,236 square miles (10,970 km2) centred near 33°08′N 107°11′W.

Truth or Consequences is the county seat and largest city; its postal code is 87901. The
county holds 2 cities, 1 village and 14 smaller communities, and it runs on Mountain Time. Its
FIPS code is 35051.

Towns & Villages in Sierra County

Sierra County has 17 named places on record: 3 incorporated cities and one village, 7 census
designated places (CDPs) with no local government of their own, and 7 unincorporated
communities. Several are mining-era settlements that never regained the population they held a
century ago.

Kingston and Hillsboro sit three miles apart in the Black Range and share a single boom-and-bust
history — Hillsboro was the county seat from 1884 to 1936, before the title moved to Hot
Springs, later renamed Truth or Consequences. This Sierra County Placitas, on Alamosa Creek near
Monticello, is unrelated to the larger Placitas near Albuquerque in Sandoval County; the two are
often confused in search results.

ZIP Codes

• 87901 — Truth or Consequences (the county’s largest post office)
• 87935 — Elephant Butte
• 87942 — Williamsburg (shares Truth or Consequences services as a de facto suburb)
• 87931 — Caballo
• 87933 — Derry
• 87939 — Monticello
• 87943 — Winston
• 88042 — Hillsboro

Arrey, Las Palomas, Kingston, Oasis, Cuchillo, Chloride, Engle, Placitas and Upham have no ZIP
code of their own; mail there is delivered under the nearest larger community’s code, most often
Truth or Consequences or Hillsboro.

Geography

Sierra County straddles the Rio Grande valley in south-central New Mexico, running from the
Black Range in the west to the San Andres Mountains on its eastern edge. Of its 4,236 square
miles, 4,179 are land and 57 are water — 1.4 percent, almost all of it Elephant Butte
Reservoir, the impoundment behind Elephant Butte Dam on the Rio Grande. The dam, completed in
1916, holds back roughly 2,065,010 acre-feet of water across 36,500 acres when full, mainly for
irrigation but also flood control and a 27.95-megawatt hydroelectric plant. Caballo Lake, a second
Rio Grande reservoir south of Truth or Consequences, was formed when Caballo Dam was built in
1938. To the west, the county’s Jornada del Muerto basin and the Black Range give way to open
desert bombing and spaceflight ranges.

Catron County lies to the northwest, Socorro County to the north, Lincoln County to the east,
Otero County to the southeast, Doña Ana County to the south, Luna County to the southwest, and
Grant County to the west. Catron County,
Socorro County,
Lincoln County,
Otero County,
Doña Ana County,
Luna County and
Grant County all border Sierra
directly.

Demographics

Sierra County had a population of 11,576 at the 2020 census, and the latest estimate puts the
county near 11,500 residents, essentially flat. Truth or Consequences and Elephant Butte are by
far the two largest communities, together holding well over two-thirds of the county’s
population. Median household income runs $41,600, well below New Mexico’s statewide figure of
$62,268. Population density works out to roughly 2.8 people per square mile of land, among the
lowest in New Mexico, and the county’s median age of 57.3 years makes it one of the oldest in the
state — both Truth or Consequences and Elephant Butte draw retirees to the area’s hot
springs and lake.

Economy & Local Life

Health care and social assistance employs the most workers in the county, about 629 people,
followed by retail trade at 532 and educational services at 396, out of roughly 3,501 employed
residents. Truth or Consequences’ geothermal hot springs anchor a small tourism and wellness
economy; by the late 1930s the town hosted about 40 spa operations, and several still draw on
natural hot-spring water today. Elephant Butte Lake State Park, New Mexico’s most-visited state
park, drives boating and fishing tourism through Elephant Butte and Williamsburg each summer.
Spaceport America, the world’s first purpose-built commercial spaceport, sits in the county’s
northeast near Upham; Virgin Galactic flew New Mexico’s first crewed spaceflight from the site on
22 May 2021. The county’s biggest annual event is Truth or Consequences’ Fiesta each May, timed
near the anniversary of the town’s 1950 name change.

History

The New Mexico Territorial Legislature organised Sierra County in 1884, naming it for the
Sierra Diablo, the Spanish name for the Black Range that dominates its western half. Hillsboro,
then a gold and silver boomtown of roughly 1,200 people, served as county seat from 1884 until
1936, when the title moved to Hot Springs on the Rio Grande. Kingston, three miles from Hillsboro,
grew even faster on silver — nearly 6,000,000 ounces came out of its 27 mines between 1883
and 1893 — before the Panic of 1893 collapsed the market and the town shrank from 1,800
residents toward the 50 it counts today.

Hot Springs took its current name in a March 1950 special election, voting 1,294 to 295 to
rename itself Truth or Consequences after the NBC radio quiz show, whose host Ralph Edwards had
offered to broadcast the show’s 10th-anniversary episode from the first town willing to adopt its
name. The program aired from the renamed town the following night, and the Fiesta held each May
since commemorates it.

Getting There

Interstate 25 runs the length of the county north to south, linking Truth or Consequences and
Elephant Butte directly to Albuquerque and Las Cruces. NM 51, NM 90, NM 152 and NM 187 branch off
it toward Hillsboro, Kingston, Monticello and the Rio Grande valley communities to the south.

• Las Cruces — about 75 miles south
• Albuquerque — about 150 miles north
• Silver City — about 70 miles west
• Alamogordo — about 90 miles southeast

Sierra County Municipal Airport, just east of Truth or Consequences, handles general aviation.
Las Cruces International Airport and Albuquerque International Sunport are the nearest commercial
airports. Amtrak has no station in the county; the closest stop is the Southwest Chief line
through Lamy, near Santa Fe, over 200 miles north.

Frequently Asked Questions

Where is Sierra County located?
It sits in south-central New Mexico along the Rio Grande, about 150 miles south of Albuquerque
and 75 miles north of Las Cruces, bordered by Catron, Socorro, Lincoln, Otero, Doña Ana, Luna and
Grant counties.

What is the population of Sierra County?
11,576 at the 2020 census, with a 2024 estimate near 11,500.

How big is Sierra County?
4,236 square miles (10,970 km2), of which 4,179 square miles are land.

What is the county seat of Sierra County?
Truth or Consequences, renamed from Hot Springs in 1950, is the county seat and largest city.

How many towns and villages are in Sierra County?
Three incorporated places — Truth or Consequences, Elephant Butte and the village of
Williamsburg — plus 7 census-designated places and 7 unincorporated communities.

What ZIP codes does Sierra County use?
87901 for Truth or Consequences, 87935 for Elephant Butte, 87942 for Williamsburg, plus 87931,
87933, 87939, 87943 and 88042 for the smaller communities.

What is Sierra County known for?
Truth or Consequences’ hot springs and its 1950 name change, Elephant Butte Lake State Park, and
Spaceport America, site of Virgin Galactic’s first crewed spaceflight in 2021.

More counties in this state: Towns and villages in New Mexico.