| | South Amboy, NJ | Elizabeth, NJ | United States |
| Population | 9,320 | 135,772 | 329,725,481 |
| Female Population | 52.5% | 50.5% | 50.5% |
| Male Population | 47.5% | 49.5% | 49.5% |
| Median Age | 41.4 | 35.3 | 38.4 |
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| Population - 2010 | 8,570 | 125,260 | 309,327,143 |
| Population - 2000 | 7,913 | 120,568 | 285,036,114 |
| Population - 1990 | 7,863 | 110,002 | 251,960,433 |
| Pop. 2000 to Now | 14.9% | 6.5% | 15.6% |
| Pop. 1990 to Now | 15.7% | 16.7% | 30.8% |
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| Population Density | 6,059.8 | 11,021.4 | 93.4 |
| Land Area | 1.5 | 12.3 | 3,531,905.4 |
| Water Area | 1.1 | 1.3 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | South Amboy, NJ | Elizabeth, NJ | United States |
| Age 0 to 4 | 4.2% | 7.6% | 5.9% |
| Age 5 to 9 | 4.2% | 7.1% | 6.1% |
| Age 10 to 14 | 5.2% | 7.3% | 6.6% |
| Age 15 to 17 | 1.2% | 4.0% | 3.9% |
| Age 18 to 20 | 4.1% | 4.5% | 4.0% |
| Age 21 to 24 | 5.2% | 5.1% | 5.2% |
| Age 25 to 34 | 14.8% | 13.8% | 13.8% |
| Age 35 to 44 | 15.7% | 15.4% | 12.9% |
| Age 45 to 54 | 12.0% | 13.1% | 12.6% |
| Age 55 to 59 | 11.0% | 6.2% | 6.7% |
| Age 60 to 64 | 8.4% | 5.1% | 6.3% |
| Age 65 to 74 | 11.0% | 6.3% | 9.6% |
| Age 75 to 84 | 2.3% | 3.3% | 4.5% |
| Age 85 and over | 0.8% | 1.1% | 1.9% |
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| Race | | | |
| | South Amboy, NJ | Elizabeth, NJ | United States |
| White | 63.0% | 13.5% | 59.4% |
| Black | 10.3% | 16.9% | 12.2% |
| Asian | 2.6% | 1.7% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 1.3% | 0.4% |
| Two or More Races | 1.8% | 1.4% | 3.2% |
| Hispanic | 22.2% | 65.3% | 18.4% |
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| Marriage & Family | | | |
| | South Amboy, NJ | Elizabeth, NJ | United States |
| Married Population | 53.2% | 41.5% | 49.8% |
| Currently Married | 51.9% | 38.0% | 48.0% |
| Married but Separated | 1.3% | 3.5% | 1.8% |
| Single Population | 46.8% | 58.5% | 50.2% |
| Never Married | 32.6% | 45.0% | 33.8% |
| Divorced | 9.5% | 9.0% | 10.8% |
| Widowed | 4.7% | 4.5% | 5.6% |
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| Household Size | 2.41 | 3.02 | 2.60 |
| Households | 3,857 | 44,354 | 124,010,992 |
| Family Households | 2,750 | 31,483 | 80,755,759 |
| Married couple, w/children | 21.9% | 29.7% | 30.5% |
| Married couple, no children | 47.9% | 25.5% | 42.9% |
| Non Family Households | 1,107 | 12,871 | 43,255,233 |
| Single householder, w/children | 14.4% | 28.7% | 15.8% |
| Single householder, no children | 15.7% | 16.1% | 10.8% |