| | Diablo Grande, CA | Westley, CA | United States |
| Population | 1,111 | 576 | 329,725,481 |
| Female Population | 57.3% | 49.7% | 50.5% |
| Male Population | 42.8% | 50.4% | 49.5% |
| Median Age | 45.3 | 22.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 285 | 1,818 | 309,327,143 |
| Population - 2000 | 618 | 747 | 285,036,114 |
| Population - 1990 | 638 | 227 | 251,960,433 |
| Pop. 2000 to Now | 47.7% | 7.6% | 15.6% |
| Pop. 1990 to Now | 43.1% | 254.2% | 30.8% |
| space4 | | | |
| Population Density | 217.7 | 1,595.6 | 93.4 |
| Land Area | 5.1 | 0.4 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Diablo Grande, CA | Westley, CA | United States |
| Age 0 to 4 | 2.6% | 12.2% | 5.9% |
| Age 5 to 9 | 3.7% | 11.5% | 6.1% |
| Age 10 to 14 | 11.3% | 17.4% | 6.6% |
| Age 15 to 17 | 5.4% | 2.1% | 3.9% |
| Age 18 to 20 | 1.4% | 6.9% | 4.0% |
| Age 21 to 24 | 3.0% | 4.0% | 5.2% |
| Age 25 to 34 | 7.7% | 11.5% | 13.8% |
| Age 35 to 44 | 14.8% | 5.7% | 12.9% |
| Age 45 to 54 | 12.4% | 15.6% | 12.6% |
| Age 55 to 59 | 5.8% | 8.2% | 6.7% |
| Age 60 to 64 | 12.5% | 0.0% | 6.3% |
| Age 65 to 74 | 13.8% | 2.1% | 9.6% |
| Age 75 to 84 | 4.9% | 3.0% | 4.5% |
| Age 85 and over | 0.9% | 0.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Diablo Grande, CA | Westley, CA | United States |
| White | 64.9% | 0.0% | 59.4% |
| Black | 5.6% | 0.0% | 12.2% |
| Asian | 9.7% | 0.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 1.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 1.5% | 0.0% | 3.2% |
| Hispanic | 17.3% | 100.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Diablo Grande, CA | Westley, CA | United States |
| Married Population | 65.0% | 71.2% | 49.8% |
| Currently Married | 65.0% | 65.0% | 48.0% |
| Married but Separated | 0.0% | 6.2% | 1.8% |
| Single Population | 35.0% | 28.8% | 50.2% |
| Never Married | 21.7% | 28.8% | 33.8% |
| Divorced | 9.5% | 0.0% | 10.8% |
| Widowed | 3.8% | 0.0% | 5.6% |
| space5 | | | |
| Household Size | 2.92 | 4.36 | 2.60 |
| Households | 380 | 132 | 124,010,992 |
| Family Households | 324 | 132 | 80,755,759 |
| Married couple, w/children | 26.5% | 53.0% | 30.5% |
| Married couple, no children | 60.8% | 31.1% | 42.9% |
| Non Family Households | 56 | 0 | 43,255,233 |
| Single householder, w/children | 7.1% | 15.9% | 15.8% |
| Single householder, no children | 5.6% | 0.0% | 10.8% |