| | Vallejo, CA | Hayward, CA | United States |
| Population | 125,350 | 162,254 | 329,725,481 |
| Female Population | 51.2% | 49.3% | 50.5% |
| Male Population | 48.8% | 50.7% | 49.5% |
| Median Age | 39.8 | 36.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 116,118 | 144,662 | 309,327,143 |
| Population - 2000 | 116,760 | 140,030 | 285,036,114 |
| Population - 1990 | 109,199 | 111,498 | 251,960,433 |
| Pop. 2000 to Now | 3.4% | 12.8% | 15.6% |
| Pop. 1990 to Now | 10.6% | 41.7% | 30.8% |
| space4 | | | |
| Population Density | 4,084.1 | 3,563.1 | 93.4 |
| Land Area | 30.7 | 45.5 | 3,531,905.4 |
| Water Area | 18.9 | 18.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Vallejo, CA | Hayward, CA | United States |
| Age 0 to 4 | 5.2% | 5.9% | 5.9% |
| Age 5 to 9 | 5.9% | 5.4% | 6.1% |
| Age 10 to 14 | 6.3% | 5.9% | 6.6% |
| Age 15 to 17 | 3.6% | 3.9% | 3.9% |
| Age 18 to 20 | 3.4% | 3.7% | 4.0% |
| Age 21 to 24 | 5.4% | 5.2% | 5.2% |
| Age 25 to 34 | 14.0% | 17.3% | 13.8% |
| Age 35 to 44 | 13.5% | 14.4% | 12.9% |
| Age 45 to 54 | 12.4% | 13.0% | 12.6% |
| Age 55 to 59 | 6.7% | 6.7% | 6.7% |
| Age 60 to 64 | 7.4% | 5.9% | 6.3% |
| Age 65 to 74 | 10.4% | 7.6% | 9.6% |
| Age 75 to 84 | 4.2% | 3.5% | 4.5% |
| Age 85 and over | 1.7% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Vallejo, CA | Hayward, CA | United States |
| White | 23.5% | 15.9% | 59.4% |
| Black | 17.5% | 9.1% | 12.2% |
| Asian | 22.6% | 28.7% | 5.6% |
| Native American | 0.2% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.7% | 1.9% | 0.2% |
| Other | 1.2% | 0.4% | 0.4% |
| Two or More Races | 5.4% | 4.8% | 3.2% |
| Hispanic | 28.8% | 38.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Vallejo, CA | Hayward, CA | United States |
| Married Population | 46.7% | 48.4% | 49.8% |
| Currently Married | 44.5% | 46.7% | 48.0% |
| Married but Separated | 2.2% | 1.8% | 1.8% |
| Single Population | 53.3% | 51.6% | 50.2% |
| Never Married | 36.6% | 38.5% | 33.8% |
| Divorced | 11.2% | 8.1% | 10.8% |
| Widowed | 5.5% | 5.0% | 5.6% |
| space5 | | | |
| Household Size | 2.82 | 3.21 | 2.60 |
| Households | 43,883 | 49,524 | 124,010,992 |
| Family Households | 29,561 | 36,296 | 80,755,759 |
| Married couple, w/children | 27.9% | 34.5% | 30.5% |
| Married couple, no children | 38.5% | 34.7% | 42.9% |
| Non Family Households | 14,322 | 13,228 | 43,255,233 |
| Single householder, w/children | 20.1% | 15.7% | 15.8% |
| Single householder, no children | 13.5% | 15.2% | 10.8% |