New Mexico counties by area
Official, comparable measurements for 33 counties and county equivalents.
- 109.1–2,125.5 mi²
- 2,202.4–3,345.2 mi²
- 3,438.6–3,961.2 mi²
- 4,176.3–5,451.1 mi²
- 5,517.2–6,924.2 mi²
- 0.29–2.1 per mi²
- 2.4–5.6 per mi²
- 5.9–10 per mi²
- 11–33 per mi²
- 43–575 per mi²
Understanding New Mexico’s county areas
The land-area range runs from Los Alamos County at 109.1 mi² to Catron County at 6,924.2 mi². The largest has 63.5 times the land area of the smallest and accounts for 5.7% of the combined county land in New Mexico. Compare with every state’s largest county.
The median county-equivalent land area is 3,758 mi², above the national median of 604.5 mi². The median describes the middle of the county size distribution; it does not describe how people or development are distributed. A state with a few very large counties can have a much smaller median than its largest entry suggests.
Where water changes the picture
Sierra County has the most assigned water area, at 57 mi². It also has the highest water share, with water making up 1.3% of its total area. Water area and water percentage answer different questions: the first measures an amount, while the second measures the mix of land and water.
Across all 33 entries, water accounts for 0.2% of the combined total area. This is calculated from the summed land and water measurements, rather than averaging county percentages, which would give each small and large county equal weight.
Where people live
An estimated 2,125,498 people lived in New Mexico on July 1, 2025 (+0.4% since 2020), or 0.6% of the national total in this dataset. Bernalillo County is the most populous county equivalent, with 667,601 residents — 31.4% of the state. The largest by land, Catron County, has 3,827.
Across the state there are 18 people per square mile of land. County densities range from 575 in Bernalillo County to 0.29 in Harding County; the median county equivalent has 6.9. Switch the map above to density to see where the state’s population concentrates.
Compare the largest and smallest county equivalents in New Mexico to see land, water, and total area on the same scale.
These calculations use the 2026 Census county records listed below. County-equivalent boundaries vary between states; area alone does not measure population, density, or usable land. See coverage and calculation rules.
Complete area table
Sorted from largest to smallest land area.
| # | County / equivalent | Land | Water | Water share | Population | Per mi² |
|---|---|---|---|---|---|---|
| 1 | Catron CountyGEOID 35003 | 6,924.2 mi² | 5.5 mi² | 0.1% | 3,827 | 0.55 |
| 2 | Socorro CountyGEOID 35053 | 6,646.4 mi² | 1.9 mi² | 0% | 15,838 | 2.4 |
| 3 | Otero CountyGEOID 35035 | 6,612.6 mi² | 14.3 mi² | 0.2% | 70,368 | 11 |
| 4 | Chaves CountyGEOID 35005 | 6,067.2 mi² | 7.9 mi² | 0.1% | 63,364 | 10 |
| 5 | Rio Arriba CountyGEOID 35039 | 5,860.9 mi² | 35.3 mi² | 0.6% | 39,832 | 6.8 |
| 6 | San Juan CountyGEOID 35045 | 5,517.2 mi² | 21.2 mi² | 0.4% | 120,340 | 22 |
| 7 | McKinley CountyGEOID 35031 | 5,451.1 mi² | 4.9 mi² | 0.1% | 68,119 | 12 |
| 8 | Lincoln CountyGEOID 35027 | 4,831.1 mi² | 0.2 mi² | 0% | 19,844 | 4.1 |
| 9 | San Miguel CountyGEOID 35047 | 4,721.5 mi² | 19.8 mi² | 0.4% | 26,260 | 5.6 |
| 10 | Cibola CountyGEOID 35006 | 4,540 mi² | 2.1 mi² | 0% | 26,807 | 5.9 |
| 11 | Lea CountyGEOID 35025 | 4,391.6 mi² | 3.1 mi² | 0.1% | 74,749 | 17 |
| 12 | Sierra CountyGEOID 35051 | 4,181.2 mi² | 57 mi² | 1.3% | 11,395 | 2.7 |
| 13 | Eddy CountyGEOID 35015 | 4,176.3 mi² | 21.8 mi² | 0.5% | 62,509 | 15 |
| 14 | Grant CountyGEOID 35017 | 3,961.2 mi² | 5.9 mi² | 0.1% | 27,252 | 6.9 |
| 15 | Union CountyGEOID 35059 | 3,825.1 mi² | 6 mi² | 0.2% | 3,844 | 1 |
| 16 | Doña Ana CountyGEOID 35013 | 3,808.2 mi² | 6.8 mi² | 0.2% | 229,091 | 60 |
| 17 | Colfax CountyGEOID 35007 | 3,758 mi² | 10.2 mi² | 0.3% | 12,184 | 3.2 |
| 18 | Sandoval CountyGEOID 35043 | 3,710.2 mi² | 4.2 mi² | 0.1% | 159,565 | 43 |
| 19 | Hidalgo CountyGEOID 35023 | 3,438.6 mi² | 9.1 mi² | 0.3% | 3,929 | 1.1 |
| 20 | Torrance CountyGEOID 35057 | 3,345.2 mi² | 0.9 mi² | 0% | 16,100 | 4.8 |
| 21 | Guadalupe CountyGEOID 35019 | 3,029.8 mi² | 1.1 mi² | 0% | 4,343 | 1.4 |
| 22 | Luna CountyGEOID 35029 | 2,965.2 mi² | 0.2 mi² | 0% | 25,407 | 8.6 |
| 23 | Quay CountyGEOID 35037 | 2,874 mi² | 7.2 mi² | 0.2% | 8,454 | 2.9 |
| 24 | Roosevelt CountyGEOID 35041 | 2,446.1 mi² | 7.2 mi² | 0.3% | 18,615 | 7.6 |
| 25 | De Baca CountyGEOID 35011 | 2,323.1 mi² | 11.2 mi² | 0.5% | 1,647 | 0.71 |
| 26 | Taos CountyGEOID 35055 | 2,202.4 mi² | 1.3 mi² | 0.1% | 34,564 | 16 |
| 27 | Harding CountyGEOID 35021 | 2,125.5 mi² | 0.4 mi² | 0% | 617 | 0.29 |
| 28 | Mora CountyGEOID 35033 | 1,926.3 mi² | 2.3 mi² | 0.1% | 4,051 | 2.1 |
| 29 | Santa Fe CountyGEOID 35049 | 1,910.4 mi² | 1 mi² | 0.1% | 156,907 | 82 |
| 30 | Curry CountyGEOID 35009 | 1,405.5 mi² | 3.1 mi² | 0.2% | 46,655 | 33 |
| 31 | Bernalillo CountyGEOID 35001 | 1,161.7 mi² | 5.7 mi² | 0.5% | 667,601 | 575 |
| 32 | Valencia CountyGEOID 35061 | 1,066.7 mi² | 1.1 mi² | 0.1% | 82,013 | 77 |
| 33 | Los Alamos CountyGEOID 35028 | 109.1 mi² | 0.1 mi² | 0.1% | 19,407 | 178 |