| | South River, NJ | Hillside, NJ | United States |
| Population | 16,087 | 22,319 | 329,725,481 |
| Female Population | 49.1% | 51.4% | 50.5% |
| Male Population | 51.0% | 48.6% | 49.5% |
| Median Age | 37.1 | 36.9 | 38.4 |
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| Population - 2010 | 16,055 | 21,494 | 309,327,143 |
| Population - 2000 | 15,322 | 21,747 | 285,036,114 |
| Population - 1990 | 13,692 | 21,044 | 251,960,433 |
| Pop. 2000 to Now | 2.0% | 0.4% | 15.6% |
| Pop. 1990 to Now | 14.1% | 3.8% | 30.8% |
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| Population Density | 5,776.3 | 8,119.0 | 93.4 |
| Land Area | 2.8 | 2.7 | 3,531,905.4 |
| Water Area | 0.2 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | South River, NJ | Hillside, NJ | United States |
| Age 0 to 4 | 7.0% | 6.0% | 5.9% |
| Age 5 to 9 | 7.6% | 6.4% | 6.1% |
| Age 10 to 14 | 6.3% | 6.0% | 6.6% |
| Age 15 to 17 | 3.6% | 3.5% | 3.9% |
| Age 18 to 20 | 3.4% | 4.3% | 4.0% |
| Age 21 to 24 | 3.3% | 5.7% | 5.2% |
| Age 25 to 34 | 14.9% | 16.5% | 13.8% |
| Age 35 to 44 | 13.5% | 10.2% | 12.9% |
| Age 45 to 54 | 12.7% | 14.6% | 12.6% |
| Age 55 to 59 | 6.2% | 8.1% | 6.7% |
| Age 60 to 64 | 7.0% | 6.0% | 6.3% |
| Age 65 to 74 | 6.9% | 7.6% | 9.6% |
| Age 75 to 84 | 4.0% | 4.0% | 4.5% |
| Age 85 and over | 3.5% | 1.3% | 1.9% |
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| Race | | | |
| | South River, NJ | Hillside, NJ | United States |
| White | 61.9% | 19.9% | 59.4% |
| Black | 7.8% | 49.3% | 12.2% |
| Asian | 2.6% | 2.0% | 5.6% |
| Native American | 0.0% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.0% | 0.2% |
| Other | 1.6% | 3.8% | 0.4% |
| Two or More Races | 1.8% | 1.6% | 3.2% |
| Hispanic | 24.1% | 23.2% | 18.4% |
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| Marriage & Family | | | |
| | South River, NJ | Hillside, NJ | United States |
| Married Population | 52.3% | 43.7% | 49.8% |
| Currently Married | 50.6% | 41.2% | 48.0% |
| Married but Separated | 1.7% | 2.5% | 1.8% |
| Single Population | 47.7% | 56.3% | 50.2% |
| Never Married | 33.3% | 40.6% | 33.8% |
| Divorced | 7.7% | 8.9% | 10.8% |
| Widowed | 6.6% | 6.8% | 5.6% |
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| Household Size | 2.84 | 3.10 | 2.60 |
| Households | 5,658 | 7,191 | 124,010,992 |
| Family Households | 4,121 | 5,512 | 80,755,759 |
| Married couple, w/children | 29.2% | 25.3% | 30.5% |
| Married couple, no children | 41.0% | 33.9% | 42.9% |
| Non Family Households | 1,537 | 1,679 | 43,255,233 |
| Single householder, w/children | 17.4% | 21.3% | 15.8% |
| Single householder, no children | 12.4% | 19.5% | 10.8% |