Admitted to the Union on January 6, 1912 as the 47th state. Prior to statehood, enumerated as New Mexico Territory 1850 – 1910.
- 1850 – 1940 federal censuses extant for all counties except for 1890.
| Bernalillo | Catron | Chaves | Cibola |
| Colfax | Curry | De Baca | Dona Ana |
| Eddy | Grant | Guadalupe | Harding |
| Hidalgo | Lea | Lincoln | Los Alamos |
| Luna | McKinley | Mora | Otero |
| Quay | Rio Arriba | Roosevelt | Sandoval |
| San Juan | San Miguel | Santa Fe | Sierra |
| Socorro | Taos | Torrance | Union |
| Valencia |