| | Stillwater, NJ | Waldwick, NJ | United States |
| Population | 3,988 | 10,086 | 329,725,481 |
| Female Population | 46.4% | 52.6% | 50.5% |
| Male Population | 53.6% | 47.4% | 49.5% |
| Median Age | 52.3 | 38.9 | 38.4 |
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| Population - 2010 | 4,150 | 9,587 | 309,327,143 |
| Population - 2000 | 4,267 | 9,622 | 285,036,114 |
| Population - 1990 | 4,253 | 9,757 | 251,960,433 |
| Pop. 2000 to Now | -9.7% | 6.6% | 15.6% |
| Pop. 1990 to Now | -9.4% | 5.2% | 30.8% |
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| Population Density | 149.6 | 4,929.6 | 93.4 |
| Land Area | 26.7 | 2.0 | 3,531,905.4 |
| Water Area | 1.3 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Stillwater, NJ | Waldwick, NJ | United States |
| Age 0 to 4 | 2.4% | 8.4% | 5.9% |
| Age 5 to 9 | 3.8% | 9.7% | 6.1% |
| Age 10 to 14 | 3.1% | 6.2% | 6.6% |
| Age 15 to 17 | 3.9% | 2.8% | 3.9% |
| Age 18 to 20 | 4.2% | 1.9% | 4.0% |
| Age 21 to 24 | 2.9% | 3.0% | 5.2% |
| Age 25 to 34 | 13.4% | 10.2% | 13.8% |
| Age 35 to 44 | 4.8% | 15.1% | 12.9% |
| Age 45 to 54 | 19.0% | 11.2% | 12.6% |
| Age 55 to 59 | 12.3% | 7.8% | 6.7% |
| Age 60 to 64 | 4.3% | 6.1% | 6.3% |
| Age 65 to 74 | 16.3% | 9.0% | 9.6% |
| Age 75 to 84 | 8.7% | 4.7% | 4.5% |
| Age 85 and over | 1.0% | 4.0% | 1.9% |
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| Race | | | |
| | Stillwater, NJ | Waldwick, NJ | United States |
| White | 96.5% | 74.2% | 59.4% |
| Black | 0.0% | 1.6% | 12.2% |
| Asian | 0.0% | 7.7% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 1.1% | 0.4% | 0.4% |
| Two or More Races | 0.2% | 1.2% | 3.2% |
| Hispanic | 2.2% | 14.9% | 18.4% |
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| Marriage & Family | | | |
| | Stillwater, NJ | Waldwick, NJ | United States |
| Married Population | 57.4% | 66.9% | 49.8% |
| Currently Married | 54.9% | 66.8% | 48.0% |
| Married but Separated | 2.5% | 0.1% | 1.8% |
| Single Population | 42.6% | 33.1% | 50.2% |
| Never Married | 28.1% | 20.4% | 33.8% |
| Divorced | 12.1% | 6.0% | 10.8% |
| Widowed | 2.4% | 6.7% | 5.6% |
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| Household Size | 2.53 | 3.01 | 2.60 |
| Households | 1,574 | 3,354 | 124,010,992 |
| Family Households | 1,220 | 2,717 | 80,755,759 |
| Married couple, w/children | 12.6% | 40.3% | 30.5% |
| Married couple, no children | 63.6% | 47.4% | 42.9% |
| Non Family Households | 354 | 637 | 43,255,233 |
| Single householder, w/children | 9.7% | 5.2% | 15.8% |
| Single householder, no children | 14.1% | 7.1% | 10.8% |