| | Union township, NJ | Warren, NJ | United States |
| Population | 59,825 | 15,850 | 329,725,481 |
| Female Population | 51.8% | 48.0% | 50.5% |
| Male Population | 48.2% | 52.0% | 49.5% |
| Median Age | 42.5 | 45.7 | 38.4 |
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| Population - 2010 | 56,813 | 15,350 | 309,327,143 |
| Population - 2000 | 54,405 | 14,259 | 285,036,114 |
| Population - 1990 | 50,024 | 10,830 | 251,960,433 |
| Pop. 2000 to Now | 9.8% | 9.7% | 15.6% |
| Pop. 1990 to Now | 19.4% | 44.4% | 30.8% |
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| Population Density | 6,594.5 | 810.7 | 93.4 |
| Land Area | 9.1 | 19.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Union township, NJ | Warren, NJ | United States |
| Age 0 to 4 | 4.2% | 4.9% | 5.9% |
| Age 5 to 9 | 4.6% | 3.9% | 6.1% |
| Age 10 to 14 | 5.2% | 9.0% | 6.6% |
| Age 15 to 17 | 3.7% | 5.9% | 3.9% |
| Age 18 to 20 | 4.1% | 3.2% | 4.0% |
| Age 21 to 24 | 5.0% | 3.4% | 5.2% |
| Age 25 to 34 | 12.9% | 7.5% | 13.8% |
| Age 35 to 44 | 13.3% | 11.5% | 12.9% |
| Age 45 to 54 | 13.5% | 16.0% | 12.6% |
| Age 55 to 59 | 8.7% | 9.9% | 6.7% |
| Age 60 to 64 | 7.6% | 7.3% | 6.3% |
| Age 65 to 74 | 10.4% | 10.3% | 9.6% |
| Age 75 to 84 | 4.4% | 5.2% | 4.5% |
| Age 85 and over | 2.4% | 1.9% | 1.9% |
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| Race | | | |
| | Union township, NJ | Warren, NJ | United States |
| White | 32.0% | 70.9% | 59.4% |
| Black | 34.9% | 2.1% | 12.2% |
| Asian | 10.8% | 16.5% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.0% | 0.2% |
| Other | 2.8% | 0.6% | 0.4% |
| Two or More Races | 2.4% | 2.2% | 3.2% |
| Hispanic | 16.9% | 7.6% | 18.4% |
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| Marriage & Family | | | |
| | Union township, NJ | Warren, NJ | United States |
| Married Population | 52.1% | 65.7% | 49.8% |
| Currently Married | 50.8% | 65.3% | 48.0% |
| Married but Separated | 1.3% | 0.4% | 1.8% |
| Single Population | 47.9% | 34.3% | 50.2% |
| Never Married | 34.2% | 25.5% | 33.8% |
| Divorced | 7.1% | 5.2% | 10.8% |
| Widowed | 6.6% | 3.6% | 5.6% |
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| Household Size | 2.80 | 2.91 | 2.60 |
| Households | 20,775 | 5,386 | 124,010,992 |
| Family Households | 15,233 | 4,666 | 80,755,759 |
| Married couple, w/children | 31.3% | 40.8% | 30.5% |
| Married couple, no children | 44.9% | 47.2% | 42.9% |
| Non Family Households | 5,542 | 720 | 43,255,233 |
| Single householder, w/children | 10.1% | 4.0% | 15.8% |
| Single householder, no children | 13.7% | 8.0% | 10.8% |