| | Castroville, CA | Bellingham, WA | United States |
| Population | 6,665 | 90,545 | 329,725,481 |
| Female Population | 50.8% | 51.5% | 50.5% |
| Male Population | 49.2% | 48.5% | 49.5% |
| Median Age | 29.3 | 33.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 5,490 | 81,705 | 309,327,143 |
| Population - 2000 | 6,724 | 67,171 | 285,036,114 |
| Population - 1990 | 5,272 | 52,179 | 251,960,433 |
| Pop. 2000 to Now | -0.4% | 39.9% | 15.6% |
| Pop. 1990 to Now | 27.1% | 80.1% | 30.8% |
| space4 | | | |
| Population Density | 6,521.5 | 3,269.1 | 93.4 |
| Land Area | 1.0 | 27.7 | 3,531,905.4 |
| Water Area | 0.0 | 2.6 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Castroville, CA | Bellingham, WA | United States |
| Age 0 to 4 | 8.7% | 3.4% | 5.9% |
| Age 5 to 9 | 12.6% | 4.0% | 6.1% |
| Age 10 to 14 | 7.8% | 3.6% | 6.6% |
| Age 15 to 17 | 3.5% | 2.4% | 3.9% |
| Age 18 to 20 | 3.0% | 9.6% | 4.0% |
| Age 21 to 24 | 4.5% | 13.2% | 5.2% |
| Age 25 to 34 | 20.8% | 15.7% | 13.8% |
| Age 35 to 44 | 13.6% | 11.8% | 12.9% |
| Age 45 to 54 | 6.7% | 9.8% | 12.6% |
| Age 55 to 59 | 2.6% | 4.9% | 6.7% |
| Age 60 to 64 | 4.8% | 5.8% | 6.3% |
| Age 65 to 74 | 9.6% | 9.5% | 9.6% |
| Age 75 to 84 | 1.2% | 4.5% | 4.5% |
| Age 85 and over | 0.7% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Castroville, CA | Bellingham, WA | United States |
| White | 9.7% | 77.4% | 59.4% |
| Black | 0.8% | 1.3% | 12.2% |
| Asian | 2.7% | 5.7% | 5.6% |
| Native American | 0.0% | 0.8% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 2.8% | 5.1% | 3.2% |
| Hispanic | 84.1% | 9.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Castroville, CA | Bellingham, WA | United States |
| Married Population | 49.7% | 38.7% | 49.8% |
| Currently Married | 48.7% | 37.6% | 48.0% |
| Married but Separated | 1.0% | 1.1% | 1.8% |
| Single Population | 50.3% | 61.3% | 50.2% |
| Never Married | 39.1% | 47.0% | 33.8% |
| Divorced | 7.7% | 10.4% | 10.8% |
| Widowed | 3.5% | 3.9% | 5.6% |
| space5 | | | |
| Household Size | 4.50 | 2.18 | 2.60 |
| Households | 1,479 | 39,496 | 124,010,992 |
| Family Households | 1,354 | 18,062 | 80,755,759 |
| Married couple, w/children | 39.1% | 25.9% | 30.5% |
| Married couple, no children | 26.9% | 51.2% | 42.9% |
| Non Family Households | 125 | 21,434 | 43,255,233 |
| Single householder, w/children | 29.5% | 13.6% | 15.8% |
| Single householder, no children | 4.4% | 9.3% | 10.8% |