| County | FIPS Code | County Seat | Established in | Population | Area (sq mi) | Area (km2) |
|---|---|---|---|---|---|---|
| Bernalillo County | 1 | Albuquerque | 1852 | 679,121 | 1,166 | 3,020 |
| Catron County | 3 | Reserve | 1921 | 3,527 | 6,928 | 17,943 |
| Chaves County | 5 | Roswell | 1889 | 64,615 | 6,071 | 15,724 |
| Cibola County | 6 | Grants | 1981 | 26,675 | 4,540 | 11,759 |
| Colfax County | 7 | Raton | 1869 | 11,941 | 3,757 | 9,731 |
| Curry County | 9 | Clovis | 1909 | 48,954 | 1,406 | 3,642 |
| De Baca County | 11 | Fort Sumner | 1917 | 1,748 | 2,325 | 6,022 |
| Doña Ana County | 13 | Las Cruces | 1852 | 218,195 | 3,807 | 9,860 |
| Eddy County | 15 | Carlsbad | 1887 | 58,460 | 4,182 | 10,831 |
| Grant County | 17 | Silver City | 1868 | 26,998 | 3,966 | 10,272 |
| Guadalupe County | 19 | Santa Rosa | 1891 | 4,300 | 3,031 | 7,850 |
| Harding County | 21 | Mosquero | 1921 | 625 | 2,126 | 5,506 |
| Hidalgo County | 23 | Lordsburg | 1920 | 4,198 | 3,446 | 8,925 |
| Lea County | 25 | Lovington | 1917 | 71,070 | 4,393 | 11,378 |
| Lincoln County | 27 | Carrizozo | 1869 | 19,572 | 4,831 | 12,512 |
| Los Alamos County | 28 | Los Alamos | 1949 | 19,369 | 109 | 282 |
| Luna County | 29 | Deming | 1901 | 23,709 | 2,965 | 7,679 |
| McKinley County | 31 | Gallup | 1899 | 71,367 | 5,449 | 14,113 |
| Mora County | 33 | Mora | 1859 | 4,521 | 1,931 | 5,001 |
| Otero County | 35 | Alamogordo | 1899 | 67,490 | 6,627 | 17,164 |
| Quay County | 37 | Tucumcari | 1903 | 8,253 | 2,855 | 7,394 |
| Rio Arriba County | 39 | Tierra Amarilla | 1852 | 38,921 | 5,858 | 15,172 |
| Roosevelt County | 41 | Portales | 1903 | 18,500 | 2,449 | 6,343 |
| Sandoval County | 43 | Bernalillo | 1903 | 146,748 | 3,710 | 9,609 |
| San Juan County | 45 | Aztec | 1887 | 123,958 | 5,514 | 14,281 |
| San Miguel County | 47 | Las Vegas | 1852 | 27,277 | 4,717 | 12,217 |
| Santa Fe County | 49 | Santa Fe | 1852 | 150,358 | 1,909 | 4,944 |
| Sierra County | 51 | Truth or Consequences | 1884 | 10,791 | 4,180 | 10,826 |
| Socorro County | 53 | Socorro | 1852 | 16,637 | 6,647 | 17,216 |
| Taos County | 55 | Taos | 1852 | 32,723 | 2,203 | 5,706 |
| Torrance County | 57 | Estancia | 1903 | 15,461 | 3,345 | 8,664 |
| Union County | 59 | Clayton | 1893 | 4,059 | 3,830 | 9,920 |
| Valencia County | 61 | Los Lunas | 1852 | 76,688 | 1,068 | 2,766 |
