| County | Rank | Change (2020) ↓ | 2026 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Valencia County | 1 | 8.68% | 83,132 | 76,495 |
| Sandoval County | 2 | 8.21% | 161,519 | 149,271 |
| Torrance County | 3 | 7.96% | 16,258 | 15,059 |
| Catron County | 4 | 6.18% | 3,831 | 3,608 |
| Doña Ana County | 5 | 4.55% | 230,078 | 220,059 |
| Otero County | 6 | 3.31% | 70,112 | 67,868 |
| Eddy County | 7 | 1.4% | 63,219 | 62,344 |
| Santa Fe County | 8 | 0.92% | 156,494 | 155,068 |
| Taos County | 9 | 0.66% | 34,687 | 34,459 |
| Lea County | 10 | 0.56% | 75,052 | 74,634 |
| Los Alamos County | 11 | -0.14% | 19,387 | 19,414 |
| Cibola County | 12 | -0.39% | 26,859 | 26,963 |
| San Juan County | 13 | -1.01% | 120,155 | 121,384 |
| Luna County | 14 | -1.03% | 25,191 | 25,452 |
| Rio Arriba County | 15 | -1.33% | 39,716 | 40,253 |
| Sierra County | 16 | -1.6% | 11,377 | 11,562 |
| Bernalillo County | 17 | -1.75% | 665,021 | 676,867 |
| Colfax County | 18 | -2.4% | 12,057 | 12,354 |
| De Baca County | 19 | -2.55% | 1,644 | 1,687 |
| Guadalupe County | 20 | -2.61% | 4,324 | 4,440 |
| Lincoln County | 21 | -3.23% | 19,652 | 20,308 |
| Chaves County | 22 | -3.33% | 62,982 | 65,154 |
| Roosevelt County | 23 | -3.7% | 18,445 | 19,153 |
| San Miguel County | 24 | -3.86% | 26,086 | 27,134 |
| Quay County | 25 | -3.99% | 8,366 | 8,714 |
| Grant County | 26 | -4.22% | 27,013 | 28,203 |
| Mora County | 27 | -4.32% | 4,010 | 4,191 |
| Socorro County | 28 | -4.86% | 15,746 | 16,551 |
| Curry County | 29 | -5.04% | 45,933 | 48,372 |
| Harding County | 30 | -5.98% | 613 | 652 |
| Hidalgo County | 31 | -6.15% | 3,907 | 4,163 |
| McKinley County | 32 | -6.8% | 67,607 | 72,540 |
| Union County | 33 | -7.89% | 3,749 | 4,070 |
New Mexico's counties show varied growth patterns from 2020 to 2026. Valencia County leads with 1.4% annualized growth, followed by Sandoval County (1.32%) and Torrance County (1.29%). The largest counties are Bernalillo County (665,021), Doña Ana County (230,078), and Sandoval County (161,519). Of the 33 counties in New Mexico, 10 are growing while 23 have experienced population decline. Overall, counties averaged -0.19% annualized growth, with total population growing by 0.05% annually.
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