| | Oak Hills, CA | Richland, WA | United States |
| Population | 9,123 | 59,718 | 329,725,481 |
| Female Population | 43.5% | 48.9% | 50.5% |
| Male Population | 56.5% | 51.2% | 49.5% |
| Median Age | 40.3 | 36.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 8,054 | 48,877 | 309,327,143 |
| Population - 2000 | 4,597 | 38,708 | 285,036,114 |
| Population - 1990 | 2,336 | 32,315 | 251,960,433 |
| Pop. 2000 to Now | 137.4% | 53.6% | 15.6% |
| Pop. 1990 to Now | 367.2% | 83.9% | 30.8% |
| space4 | | | |
| Population Density | 374.7 | 1,529.2 | 93.4 |
| Land Area | 24.4 | 39.1 | 3,531,905.4 |
| Water Area | 0.0 | 3.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Oak Hills, CA | Richland, WA | United States |
| Age 0 to 4 | 4.8% | 6.2% | 5.9% |
| Age 5 to 9 | 6.9% | 7.8% | 6.1% |
| Age 10 to 14 | 6.7% | 6.6% | 6.6% |
| Age 15 to 17 | 2.6% | 4.2% | 3.9% |
| Age 18 to 20 | 2.9% | 3.1% | 4.0% |
| Age 21 to 24 | 7.4% | 5.4% | 5.2% |
| Age 25 to 34 | 15.0% | 14.8% | 13.8% |
| Age 35 to 44 | 14.9% | 13.1% | 12.9% |
| Age 45 to 54 | 5.1% | 10.7% | 12.6% |
| Age 55 to 59 | 7.8% | 6.5% | 6.7% |
| Age 60 to 64 | 7.8% | 6.1% | 6.3% |
| Age 65 to 74 | 12.2% | 8.9% | 9.6% |
| Age 75 to 84 | 4.4% | 4.8% | 4.5% |
| Age 85 and over | 1.6% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Oak Hills, CA | Richland, WA | United States |
| White | 34.2% | 76.1% | 59.4% |
| Black | 2.2% | 1.5% | 12.2% |
| Asian | 3.1% | 5.7% | 5.6% |
| Native American | 0.1% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.7% | 0.1% | 0.2% |
| Other | 0.0% | 0.5% | 0.4% |
| Two or More Races | 0.2% | 3.4% | 3.2% |
| Hispanic | 59.5% | 12.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Oak Hills, CA | Richland, WA | United States |
| Married Population | 57.5% | 51.8% | 49.8% |
| Currently Married | 54.6% | 50.2% | 48.0% |
| Married but Separated | 2.9% | 1.6% | 1.8% |
| Single Population | 42.5% | 48.2% | 50.2% |
| Never Married | 30.5% | 31.3% | 33.8% |
| Divorced | 9.1% | 12.5% | 10.8% |
| Widowed | 2.9% | 4.3% | 5.6% |
| space5 | | | |
| Household Size | 3.24 | 2.55 | 2.60 |
| Households | 2,816 | 23,335 | 124,010,992 |
| Family Households | 2,145 | 14,887 | 80,755,759 |
| Married couple, w/children | 45.9% | 30.6% | 30.5% |
| Married couple, no children | 45.6% | 44.1% | 42.9% |
| Non Family Households | 671 | 8,448 | 43,255,233 |
| Single householder, w/children | 5.1% | 16.8% | 15.8% |
| Single householder, no children | 3.4% | 8.6% | 10.8% |