| | Milltown, NJ | South Brunswick, NJ | United States |
| Population | 7,019 | 46,623 | 329,725,481 |
| Female Population | 55.2% | 51.2% | 50.5% |
| Male Population | 44.8% | 48.8% | 49.5% |
| Median Age | 41.3 | 41.4 | 38.4 |
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| Population - 2010 | 6,891 | 43,553 | 309,327,143 |
| Population - 2000 | 7,000 | 37,734 | 285,036,114 |
| Population - 1990 | 6,968 | 25,792 | 251,960,433 |
| Pop. 2000 to Now | -1.3% | 20.2% | 15.6% |
| Pop. 1990 to Now | -0.9% | 75.9% | 30.8% |
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| Population Density | 4,516.7 | 1,147.0 | 93.4 |
| Land Area | 1.6 | 40.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.4 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Milltown, NJ | South Brunswick, NJ | United States |
| Age 0 to 4 | 6.6% | 4.8% | 5.9% |
| Age 5 to 9 | 5.2% | 7.0% | 6.1% |
| Age 10 to 14 | 8.5% | 6.9% | 6.6% |
| Age 15 to 17 | 3.6% | 5.4% | 3.9% |
| Age 18 to 20 | 1.1% | 2.9% | 4.0% |
| Age 21 to 24 | 2.8% | 3.4% | 5.2% |
| Age 25 to 34 | 11.2% | 10.3% | 13.8% |
| Age 35 to 44 | 15.3% | 14.4% | 12.9% |
| Age 45 to 54 | 12.3% | 18.4% | 12.6% |
| Age 55 to 59 | 9.9% | 7.9% | 6.7% |
| Age 60 to 64 | 9.4% | 5.9% | 6.3% |
| Age 65 to 74 | 8.2% | 8.5% | 9.6% |
| Age 75 to 84 | 3.3% | 3.1% | 4.5% |
| Age 85 and over | 2.6% | 1.2% | 1.9% |
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| Race | | | |
| | Milltown, NJ | South Brunswick, NJ | United States |
| White | 82.2% | 35.2% | 59.4% |
| Black | 2.8% | 6.0% | 12.2% |
| Asian | 4.2% | 47.5% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 1.0% | 0.4% |
| Two or More Races | 3.6% | 2.8% | 3.2% |
| Hispanic | 7.0% | 7.3% | 18.4% |
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| Marriage & Family | | | |
| | Milltown, NJ | South Brunswick, NJ | United States |
| Married Population | 56.3% | 65.4% | 49.8% |
| Currently Married | 54.8% | 64.9% | 48.0% |
| Married but Separated | 1.5% | 0.5% | 1.8% |
| Single Population | 43.7% | 34.6% | 50.2% |
| Never Married | 21.0% | 25.7% | 33.8% |
| Divorced | 14.3% | 5.1% | 10.8% |
| Widowed | 8.4% | 3.7% | 5.6% |
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| Household Size | 2.77 | 2.79 | 2.60 |
| Households | 2,529 | 16,706 | 124,010,992 |
| Family Households | 1,855 | 13,168 | 80,755,759 |
| Married couple, w/children | 34.7% | 46.0% | 30.5% |
| Married couple, no children | 36.1% | 43.2% | 42.9% |
| Non Family Households | 674 | 3,538 | 43,255,233 |
| Single householder, w/children | 12.2% | 5.5% | 15.8% |
| Single householder, no children | 17.0% | 5.3% | 10.8% |