| | Willingboro, NJ | Hamilton township (Mercer County), NJ | United States |
| Population | 31,763 | 91,557 | 329,725,481 |
| Female Population | 51.6% | 50.3% | 50.5% |
| Male Population | 48.4% | 49.7% | 49.5% |
| Median Age | 40.8 | 41.8 | 38.4 |
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| Population - 2010 | 31,632 | 88,512 | 309,327,143 |
| Population - 2000 | 33,008 | 87,109 | 285,036,114 |
| Population - 1990 | 36,291 | 86,553 | 251,960,433 |
| Pop. 2000 to Now | -3.0% | -0.4% | 15.6% |
| Pop. 1990 to Now | -11.8% | 0.2% | 30.8% |
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| Population Density | 4,104.8 | 2,318.0 | 93.4 |
| Land Area | 7.7 | 39.5 | 3,531,905.4 |
| Water Area | 0.4 | 0.9 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Willingboro, NJ | Hamilton township (Mercer County), NJ | United States |
| Age 0 to 4 | 6.0% | 5.6% | 5.9% |
| Age 5 to 9 | 5.3% | 4.6% | 6.1% |
| Age 10 to 14 | 4.6% | 4.2% | 6.6% |
| Age 15 to 17 | 3.0% | 3.6% | 3.9% |
| Age 18 to 20 | 4.0% | 3.2% | 4.0% |
| Age 21 to 24 | 5.4% | 5.2% | 5.2% |
| Age 25 to 34 | 14.9% | 14.3% | 13.8% |
| Age 35 to 44 | 11.0% | 12.7% | 12.9% |
| Age 45 to 54 | 13.2% | 13.0% | 12.6% |
| Age 55 to 59 | 7.6% | 7.1% | 6.7% |
| Age 60 to 64 | 7.0% | 7.3% | 6.3% |
| Age 65 to 74 | 10.5% | 10.9% | 9.6% |
| Age 75 to 84 | 5.5% | 6.0% | 4.5% |
| Age 85 and over | 2.0% | 2.3% | 1.9% |
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| Race | | | |
| | Willingboro, NJ | Hamilton township (Mercer County), NJ | United States |
| White | 12.2% | 63.7% | 59.4% |
| Black | 67.0% | 12.5% | 12.2% |
| Asian | 1.5% | 5.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.4% | 0.1% | 0.4% |
| Two or More Races | 5.7% | 1.5% | 3.2% |
| Hispanic | 13.2% | 17.2% | 18.4% |
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| Marriage & Family | | | |
| | Willingboro, NJ | Hamilton township (Mercer County), NJ | United States |
| Married Population | 44.0% | 51.2% | 49.8% |
| Currently Married | 41.4% | 48.9% | 48.0% |
| Married but Separated | 2.7% | 2.3% | 1.8% |
| Single Population | 56.0% | 48.8% | 50.2% |
| Never Married | 39.3% | 33.6% | 33.8% |
| Divorced | 10.5% | 9.2% | 10.8% |
| Widowed | 6.2% | 6.0% | 5.6% |
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| Household Size | 2.96 | 2.62 | 2.60 |
| Households | 10,708 | 34,682 | 124,010,992 |
| Family Households | 8,015 | 23,678 | 80,755,759 |
| Married couple, w/children | 21.1% | 27.3% | 30.5% |
| Married couple, no children | 41.6% | 45.9% | 42.9% |
| Non Family Households | 2,693 | 11,004 | 43,255,233 |
| Single householder, w/children | 20.2% | 13.0% | 15.8% |
| Single householder, no children | 17.1% | 13.9% | 10.8% |