| | Bethlehem township, PA | Bridgewater, NJ | United States |
| Population | 25,662 | 46,072 | 329,725,481 |
| Female Population | 50.5% | 52.5% | 50.5% |
| Male Population | 49.5% | 47.5% | 49.5% |
| Median Age | 43.6 | 43.6 | 38.4 |
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| Population - 2010 | 23,794 | 44,485 | 309,327,143 |
| Population - 2000 | 21,171 | 42,940 | 285,036,114 |
| Population - 1990 | 16,425 | 32,509 | 251,960,433 |
| Pop. 2000 to Now | 16.0% | 2.4% | 15.6% |
| Pop. 1990 to Now | 49.5% | 35.2% | 30.8% |
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| Population Density | 1,778.1 | 1,438.1 | 93.4 |
| Land Area | 14.4 | 32.0 | 3,531,905.4 |
| Water Area | 0.2 | 0.5 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Bethlehem township, PA | Bridgewater, NJ | United States |
| Age 0 to 4 | 5.2% | 5.0% | 5.9% |
| Age 5 to 9 | 4.0% | 5.4% | 6.1% |
| Age 10 to 14 | 5.7% | 7.5% | 6.6% |
| Age 15 to 17 | 3.9% | 4.6% | 3.9% |
| Age 18 to 20 | 4.8% | 3.2% | 4.0% |
| Age 21 to 24 | 4.6% | 4.5% | 5.2% |
| Age 25 to 34 | 12.9% | 7.8% | 13.8% |
| Age 35 to 44 | 11.0% | 13.7% | 12.9% |
| Age 45 to 54 | 12.0% | 16.1% | 12.6% |
| Age 55 to 59 | 8.5% | 8.2% | 6.7% |
| Age 60 to 64 | 8.3% | 6.6% | 6.3% |
| Age 65 to 74 | 10.4% | 8.6% | 9.6% |
| Age 75 to 84 | 5.3% | 6.0% | 4.5% |
| Age 85 and over | 3.5% | 2.6% | 1.9% |
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| Race | | | |
| | Bethlehem township, PA | Bridgewater, NJ | United States |
| White | 74.0% | 61.8% | 59.4% |
| Black | 5.6% | 2.0% | 12.2% |
| Asian | 5.3% | 24.8% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.5% | 0.0% | 0.2% |
| Other | 0.4% | 0.0% | 0.4% |
| Two or More Races | 1.5% | 2.3% | 3.2% |
| Hispanic | 12.7% | 9.0% | 18.4% |
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| Marriage & Family | | | |
| | Bethlehem township, PA | Bridgewater, NJ | United States |
| Married Population | 57.6% | 60.1% | 49.8% |
| Currently Married | 55.6% | 59.3% | 48.0% |
| Married but Separated | 2.0% | 0.8% | 1.8% |
| Single Population | 42.4% | 39.9% | 50.2% |
| Never Married | 28.6% | 26.0% | 33.8% |
| Divorced | 7.6% | 7.9% | 10.8% |
| Widowed | 6.2% | 6.1% | 5.6% |
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| Household Size | 2.55 | 2.82 | 2.60 |
| Households | 9,760 | 16,085 | 124,010,992 |
| Family Households | 6,924 | 12,184 | 80,755,759 |
| Married couple, w/children | 31.3% | 42.6% | 30.5% |
| Married couple, no children | 51.6% | 43.2% | 42.9% |
| Non Family Households | 2,836 | 3,901 | 43,255,233 |
| Single householder, w/children | 8.7% | 6.3% | 15.8% |
| Single householder, no children | 8.4% | 7.8% | 10.8% |