San Juan County, New Mexico

A county in New Mexico, ranked 5 of 33 by population.

CountyFIPS 35045

Within New Mexico

San Juan County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Aztec, the county seat, located via the 2025 Census Gazetteer.

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Population: 120,340; -1,044 (-0.9%) since 2020
Land area: 5,517; square miles. A further 0.4% of the total area is water
Population density: 21.8; people per square mile, computed rather than published
County seat: Aztec; Seat of county government.
Established: 1887; 138 years ago
Largest city: Farmington city; Population 46,055.

Satellite view

Aerial imagery of San Juan 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 San Juan 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 632 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 San Juan 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.

Measure	Value	In New Mexico	Nationally
Population	120,340	5th of 33	539th of 3,144
Land area	5,517 sq mi	6th of 33	67th of 3,144
Population density	21.8 per sq mi	8th of 33	2,183rd of 3,144
Median household income	$55,872	14th of 32	2,413th of 3,143

Full data for San Juan County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
Measure	Value	Source and vintage
Population	120,340	Vintage 2025 Population Estimates
Population in 2020	121,384	Vintage 2025 Population Estimates
2020 estimates base?	121,665	Vintage 2025 Population Estimates
Land area	5,517 sq mi	2025 Gazetteer Files
Water area	21.2 sq mi	2025 Gazetteer Files
Total area	5,538 sq mi	2025 Gazetteer Files
Population density?	21.8 per sq mi	Computed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income	$55,872	American Community Survey 2020-2024 5-Year Estimates
Median home value	$193,800	American Community Survey 2020-2024 5-Year Estimates
Median age	38.3	American Community Survey 2020-2024 5-Year Estimates
Households	41,732	American Community Survey 2020-2024 5-Year Estimates
Housing units	48,255	American 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: -43; 1,249 births, 1,292 deaths
Net migration: -148; More people moved out than moved in.

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

The 8 areas bordering San Juan 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 area	State	Shared border	Population
McKinley County	New Mexico	80 mi	68,119
Apache County	Arizona	69 mi	64,445
Rio Arriba County	New Mexico	67 mi	39,832
La Plata County	Colorado	50 mi	56,898
Montezuma County	Colorado	37 mi	26,678
Sandoval County	New Mexico	15 mi	159,565
Archuleta County	Colorado	3.3 mi	14,306
San Juan County	Utah	a single point	14,542

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

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

Satellite view

Where San Juan County ranks

Full data for San Juan County

How the population changed

The 8 areas bordering San Juan County

All 33 counties of New Mexico