County Maps US

Sierra County, New Mexico

A county in New Mexico, ranked 25 of 33 by population.

CountyFIPS 35051

Within New Mexico
Sierra County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Truth or Consequences, the county seat, located via the 2025 Census Gazetteer.

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Population
11,395
-167 (-1.4%) since 2020
Land area
4,181
square miles. A further 1.3% of the total area is water
Population density
2.7
people per square mile, computed rather than published
County seat
Truth or Consequences
Seat of county government.
Established
1884
141 years ago
Largest city
Truth or Consequences city
Population 5,949.

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

Satellite view

Aerial imagery of Sierra County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.

Aerial view of Sierra County, New Mexico from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 800 by 535 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

Where Sierra County ranks

Position among the 33 counties of New Mexico, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn New MexicoNationally
Population11,39525th of 332,326th of 3,144
Land area4,181 sq mi12th of 33112th of 3,144
Population density2.7 per sq mi25th of 332,927th of 3,144
Median household income$41,60030th of 323,045th of 3,143

Full data for Sierra County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population11,395Vintage 2025 Population Estimates
Population in 202011,562Vintage 2025 Population Estimates
2020 estimates base?11,572Vintage 2025 Population Estimates
Land area4,181 sq mi2025 Gazetteer Files
Water area57.0 sq mi2025 Gazetteer Files
Total area4,238 sq mi2025 Gazetteer Files
Population density?2.7 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$41,600American Community Survey 2020-2024 5-Year Estimates
Median home value$152,600American Community Survey 2020-2024 5-Year Estimates
Median age57.6American Community Survey 2020-2024 5-Year Estimates
Households5,440American Community Survey 2020-2024 5-Year Estimates
Housing units8,200American Community Survey 2020-2024 5-Year Estimates

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.

How the population changed

The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:

Births minus deaths
-169
85 births, 254 deaths
Net migration
+152
More people moved in than moved out.

Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.

The 7 areas bordering Sierra County

Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.

Bordering areaStateShared borderPopulation
Socorro CountyNew Mexico78 mi15,838
Doña Ana CountyNew Mexico75 mi229,091
Grant CountyNew Mexico70 mi27,252
Catron CountyNew Mexico36 mi3,827
Otero CountyNew Mexico23 mi70,368
Luna CountyNew Mexico18 mi25,407
Lincoln CountyNew Mexico7.7 mi19,844

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

All 33 counties of New Mexico

Open the interactive New Mexico county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.