| | Portales, NM | Belen, NM | United States |
| Population | 12,151 | 7,374 | 329,725,481 |
| Female Population | 51.0% | 51.4% | 50.5% |
| Male Population | 49.0% | 48.6% | 49.5% |
| Median Age | 27.1 | 40.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 12,404 | 7,649 | 309,327,143 |
| Population - 2000 | 11,131 | 6,901 | 285,036,114 |
| Population - 1990 | 10,690 | 6,547 | 251,960,433 |
| Pop. 2000 to Now | 3.2% | 8.6% | 15.6% |
| Pop. 1990 to Now | 7.5% | 14.5% | 30.8% |
| space4 | | | |
| Population Density | 1,535.4 | 889.3 | 93.4 |
| Land Area | 7.9 | 8.3 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Portales, NM | Belen, NM | United States |
| Age 0 to 4 | 6.4% | 4.0% | 5.9% |
| Age 5 to 9 | 8.6% | 5.4% | 6.1% |
| Age 10 to 14 | 6.9% | 6.5% | 6.6% |
| Age 15 to 17 | 4.1% | 3.2% | 3.9% |
| Age 18 to 20 | 9.0% | 2.2% | 4.0% |
| Age 21 to 24 | 12.5% | 7.0% | 5.2% |
| Age 25 to 34 | 12.5% | 13.9% | 13.8% |
| Age 35 to 44 | 11.9% | 9.9% | 12.9% |
| Age 45 to 54 | 7.3% | 12.5% | 12.6% |
| Age 55 to 59 | 4.0% | 6.2% | 6.7% |
| Age 60 to 64 | 4.1% | 10.1% | 6.3% |
| Age 65 to 74 | 8.1% | 11.0% | 9.6% |
| Age 75 to 84 | 3.0% | 5.2% | 4.5% |
| Age 85 and over | 1.6% | 3.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Portales, NM | Belen, NM | United States |
| White | 45.9% | 28.0% | 59.4% |
| Black | 3.2% | 0.0% | 12.2% |
| Asian | 0.7% | 1.7% | 5.6% |
| Native American | 0.3% | 0.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.0% | 0.2% |
| Other | 0.6% | 0.0% | 0.4% |
| Two or More Races | 3.7% | 4.0% | 3.2% |
| Hispanic | 45.6% | 65.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Portales, NM | Belen, NM | United States |
| Married Population | 39.4% | 31.5% | 49.8% |
| Currently Married | 36.8% | 29.7% | 48.0% |
| Married but Separated | 2.6% | 1.8% | 1.8% |
| Single Population | 60.6% | 68.5% | 50.2% |
| Never Married | 42.2% | 39.2% | 33.8% |
| Divorced | 11.5% | 24.8% | 10.8% |
| Widowed | 6.9% | 4.5% | 5.6% |
| space5 | | | |
| Household Size | 2.63 | 2.72 | 2.60 |
| Households | 4,273 | 2,678 | 124,010,992 |
| Family Households | 2,314 | 1,558 | 80,755,759 |
| Married couple, w/children | 36.1% | 7.6% | 30.5% |
| Married couple, no children | 33.2% | 32.2% | 42.9% |
| Non Family Households | 1,959 | 1,120 | 43,255,233 |
| Single householder, w/children | 22.9% | 29.5% | 15.8% |
| Single householder, no children | 7.8% | 30.7% | 10.8% |