| | Black Diamond, WA | Brea, CA | United States |
| Population | 5,002 | 46,912 | 329,725,481 |
| Female Population | 46.4% | 52.9% | 50.5% |
| Male Population | 53.6% | 47.1% | 49.5% |
| Median Age | 39 | 40.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 4,150 | 39,449 | 309,327,143 |
| Population - 2000 | 3,970 | 35,410 | 285,036,114 |
| Population - 1990 | 1,422 | 32,873 | 251,960,433 |
| Pop. 2000 to Now | 36.1% | 25.6% | 15.6% |
| Pop. 1990 to Now | 280.0% | 35.3% | 30.8% |
| space4 | | | |
| Population Density | 766.2 | 3,850.0 | 93.4 |
| Land Area | 6.5 | 12.2 | 3,531,905.4 |
| Water Area | 0.6 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Black Diamond, WA | Brea, CA | United States |
| Age 0 to 4 | 6.8% | 5.4% | 5.9% |
| Age 5 to 9 | 5.6% | 6.2% | 6.1% |
| Age 10 to 14 | 8.6% | 6.3% | 6.6% |
| Age 15 to 17 | 2.2% | 4.2% | 3.9% |
| Age 18 to 20 | 2.3% | 3.5% | 4.0% |
| Age 21 to 24 | 2.9% | 4.6% | 5.2% |
| Age 25 to 34 | 14.4% | 13.2% | 13.8% |
| Age 35 to 44 | 15.7% | 13.0% | 12.9% |
| Age 45 to 54 | 11.6% | 15.1% | 12.6% |
| Age 55 to 59 | 9.7% | 7.3% | 6.7% |
| Age 60 to 64 | 6.6% | 5.8% | 6.3% |
| Age 65 to 74 | 8.2% | 9.5% | 9.6% |
| Age 75 to 84 | 3.5% | 3.9% | 4.5% |
| Age 85 and over | 1.8% | 2.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Black Diamond, WA | Brea, CA | United States |
| White | 80.8% | 39.6% | 59.4% |
| Black | 1.0% | 1.1% | 12.2% |
| Asian | 6.9% | 25.2% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.8% | 0.4% | 0.4% |
| Two or More Races | 2.9% | 3.8% | 3.2% |
| Hispanic | 7.5% | 29.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Black Diamond, WA | Brea, CA | United States |
| Married Population | 62.1% | 55.5% | 49.8% |
| Currently Married | 59.9% | 54.1% | 48.0% |
| Married but Separated | 2.3% | 1.5% | 1.8% |
| Single Population | 37.9% | 44.5% | 50.2% |
| Never Married | 20.8% | 31.7% | 33.8% |
| Divorced | 13.6% | 8.1% | 10.8% |
| Widowed | 3.4% | 4.7% | 5.6% |
| space5 | | | |
| Household Size | 2.61 | 2.82 | 2.60 |
| Households | 1,914 | 16,584 | 124,010,992 |
| Family Households | 1,384 | 12,322 | 80,755,759 |
| Married couple, w/children | 34.7% | 36.6% | 30.5% |
| Married couple, no children | 43.5% | 41.0% | 42.9% |
| Non Family Households | 530 | 4,262 | 43,255,233 |
| Single householder, w/children | 8.5% | 10.5% | 15.8% |
| Single householder, no children | 13.3% | 11.9% | 10.8% |