| | Selma, OR | Benicia, CA | United States |
| Population | 800 | 27,191 | 329,725,481 |
| Female Population | 53.4% | 51.2% | 50.5% |
| Male Population | 46.6% | 48.8% | 49.5% |
| Median Age | 36.6 | 45.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 649 | 27,058 | 309,327,143 |
| Population - 2000 | 652 | 26,865 | 285,036,114 |
| Population - 1990 | 554 | 24,437 | 251,960,433 |
| Pop. 2000 to Now | -6.6% | 4.2% | 15.6% |
| Pop. 1990 to Now | 9.9% | 14.5% | 30.8% |
| space4 | | | |
| Population Density | 123.9 | 2,106.5 | 93.4 |
| Land Area | 6.5 | 12.9 | 3,531,905.4 |
| Water Area | 0.0 | 2.8 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Selma, OR | Benicia, CA | United States |
| Age 0 to 4 | 3.3% | 5.0% | 5.9% |
| Age 5 to 9 | 0.0% | 5.6% | 6.1% |
| Age 10 to 14 | 15.4% | 6.2% | 6.6% |
| Age 15 to 17 | 4.0% | 4.0% | 3.9% |
| Age 18 to 20 | 1.4% | 3.0% | 4.0% |
| Age 21 to 24 | 0.0% | 3.0% | 5.2% |
| Age 25 to 34 | 15.1% | 10.3% | 13.8% |
| Age 35 to 44 | 18.8% | 12.7% | 12.9% |
| Age 45 to 54 | 4.8% | 13.5% | 12.6% |
| Age 55 to 59 | 6.6% | 8.3% | 6.7% |
| Age 60 to 64 | 11.1% | 7.4% | 6.3% |
| Age 65 to 74 | 15.1% | 13.9% | 9.6% |
| Age 75 to 84 | 2.5% | 4.7% | 4.5% |
| Age 85 and over | 2.0% | 2.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Selma, OR | Benicia, CA | United States |
| White | 97.1% | 61.4% | 59.4% |
| Black | 0.0% | 3.6% | 12.2% |
| Asian | 0.0% | 11.4% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.5% | 0.2% |
| Other | 0.0% | 0.6% | 0.4% |
| Two or More Races | 1.6% | 8.6% | 3.2% |
| Hispanic | 1.3% | 13.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Selma, OR | Benicia, CA | United States |
| Married Population | 70.0% | 54.8% | 49.8% |
| Currently Married | 70.0% | 53.8% | 48.0% |
| Married but Separated | 0.0% | 1.0% | 1.8% |
| Single Population | 30.0% | 45.2% | 50.2% |
| Never Married | 13.8% | 25.9% | 33.8% |
| Divorced | 7.7% | 13.0% | 10.8% |
| Widowed | 8.4% | 6.2% | 5.6% |
| space5 | | | |
| Household Size | 2.55 | 2.51 | 2.60 |
| Households | 312 | 10,844 | 124,010,992 |
| Family Households | 234 | 7,136 | 80,755,759 |
| Married couple, w/children | 48.7% | 31.4% | 30.5% |
| Married couple, no children | 44.0% | 48.4% | 42.9% |
| Non Family Households | 78 | 3,708 | 43,255,233 |
| Single householder, w/children | 0.0% | 13.1% | 15.8% |
| Single householder, no children | 7.3% | 7.2% | 10.8% |