| | Martinez, CA | Gastonia, NC | United States |
| Population | 37,308 | 79,483 | 329,725,481 |
| Female Population | 51.4% | 52.2% | 50.5% |
| Male Population | 48.6% | 47.8% | 49.5% |
| Median Age | 41.8 | 38 | 38.4 |
| space3 | | | |
| Population - 2010 | 36,150 | 71,716 | 309,327,143 |
| Population - 2000 | 35,866 | 66,277 | 285,036,114 |
| Population - 1990 | 31,808 | 54,732 | 251,960,433 |
| Pop. 2000 to Now | 6.0% | 17.1% | 15.6% |
| Pop. 1990 to Now | 19.6% | 41.9% | 30.8% |
| space4 | | | |
| Population Density | 2,953.7 | 1,539.0 | 93.4 |
| Land Area | 12.6 | 51.6 | 3,531,905.4 |
| Water Area | 1.0 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Martinez, CA | Gastonia, NC | United States |
| Age 0 to 4 | 7.1% | 6.2% | 5.9% |
| Age 5 to 9 | 5.1% | 7.2% | 6.1% |
| Age 10 to 14 | 5.7% | 7.2% | 6.6% |
| Age 15 to 17 | 2.6% | 4.3% | 3.9% |
| Age 18 to 20 | 3.0% | 3.8% | 4.0% |
| Age 21 to 24 | 4.2% | 4.4% | 5.2% |
| Age 25 to 34 | 12.0% | 13.5% | 13.8% |
| Age 35 to 44 | 15.3% | 13.3% | 12.9% |
| Age 45 to 54 | 13.2% | 13.4% | 12.6% |
| Age 55 to 59 | 7.9% | 5.9% | 6.7% |
| Age 60 to 64 | 7.8% | 5.4% | 6.3% |
| Age 65 to 74 | 9.7% | 9.5% | 9.6% |
| Age 75 to 84 | 4.4% | 4.2% | 4.5% |
| Age 85 and over | 2.1% | 1.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Martinez, CA | Gastonia, NC | United States |
| White | 61.0% | 55.6% | 59.4% |
| Black | 3.1% | 29.4% | 12.2% |
| Asian | 9.8% | 1.3% | 5.6% |
| Native American | 0.2% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.4% | 0.2% | 0.4% |
| Two or More Races | 6.6% | 3.3% | 3.2% |
| Hispanic | 18.9% | 10.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Martinez, CA | Gastonia, NC | United States |
| Married Population | 53.6% | 46.0% | 49.8% |
| Currently Married | 52.0% | 43.3% | 48.0% |
| Married but Separated | 1.6% | 2.8% | 1.8% |
| Single Population | 46.4% | 54.0% | 50.2% |
| Never Married | 29.9% | 34.0% | 33.8% |
| Divorced | 12.4% | 13.3% | 10.8% |
| Widowed | 4.1% | 6.7% | 5.6% |
| space5 | | | |
| Household Size | 2.48 | 2.52 | 2.60 |
| Households | 14,825 | 30,991 | 124,010,992 |
| Family Households | 9,684 | 19,139 | 80,755,759 |
| Married couple, w/children | 33.5% | 29.3% | 30.5% |
| Married couple, no children | 43.7% | 36.6% | 42.9% |
| Non Family Households | 5,141 | 11,852 | 43,255,233 |
| Single householder, w/children | 12.8% | 21.7% | 15.8% |
| Single householder, no children | 9.9% | 12.4% | 10.8% |