| | Benicia, CA | King City, CA | United States |
| Population | 27,191 | 13,419 | 329,725,481 |
| Female Population | 51.2% | 51.8% | 50.5% |
| Male Population | 48.8% | 48.2% | 49.5% |
| Median Age | 45.1 | 28.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 27,058 | 12,900 | 309,327,143 |
| Population - 2000 | 26,865 | 11,094 | 285,036,114 |
| Population - 1990 | 24,437 | 7,634 | 251,960,433 |
| Pop. 2000 to Now | 4.2% | 25.9% | 15.6% |
| Pop. 1990 to Now | 14.5% | 83.0% | 30.8% |
| space4 | | | |
| Population Density | 2,106.5 | 3,444.3 | 93.4 |
| Land Area | 12.9 | 3.9 | 3,531,905.4 |
| Water Area | 2.8 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Benicia, CA | King City, CA | United States |
| Age 0 to 4 | 5.0% | 11.2% | 5.9% |
| Age 5 to 9 | 5.6% | 11.7% | 6.1% |
| Age 10 to 14 | 6.2% | 6.6% | 6.6% |
| Age 15 to 17 | 4.0% | 6.6% | 3.9% |
| Age 18 to 20 | 3.0% | 4.5% | 4.0% |
| Age 21 to 24 | 3.0% | 5.0% | 5.2% |
| Age 25 to 34 | 10.3% | 14.2% | 13.8% |
| Age 35 to 44 | 12.7% | 16.1% | 12.9% |
| Age 45 to 54 | 13.5% | 10.2% | 12.6% |
| Age 55 to 59 | 8.3% | 3.2% | 6.7% |
| Age 60 to 64 | 7.4% | 2.8% | 6.3% |
| Age 65 to 74 | 13.9% | 5.8% | 9.6% |
| Age 75 to 84 | 4.7% | 1.3% | 4.5% |
| Age 85 and over | 2.2% | 0.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Benicia, CA | King City, CA | United States |
| White | 61.4% | 8.1% | 59.4% |
| Black | 3.6% | 0.2% | 12.2% |
| Asian | 11.4% | 4.0% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.5% | 0.0% | 0.2% |
| Other | 0.6% | 0.3% | 0.4% |
| Two or More Races | 8.6% | 0.3% | 3.2% |
| Hispanic | 13.9% | 87.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Benicia, CA | King City, CA | United States |
| Married Population | 54.8% | 48.1% | 49.8% |
| Currently Married | 53.8% | 46.9% | 48.0% |
| Married but Separated | 1.0% | 1.1% | 1.8% |
| Single Population | 45.2% | 51.9% | 50.2% |
| Never Married | 25.9% | 45.3% | 33.8% |
| Divorced | 13.0% | 4.1% | 10.8% |
| Widowed | 6.2% | 2.5% | 5.6% |
| space5 | | | |
| Household Size | 2.51 | 4.15 | 2.60 |
| Households | 10,844 | 3,218 | 124,010,992 |
| Family Households | 7,136 | 2,833 | 80,755,759 |
| Married couple, w/children | 31.4% | 43.8% | 30.5% |
| Married couple, no children | 48.4% | 22.2% | 42.9% |
| Non Family Households | 3,708 | 385 | 43,255,233 |
| Single householder, w/children | 13.1% | 22.0% | 15.8% |
| Single householder, no children | 7.2% | 12.1% | 10.8% |