| | Monroe township (Middlesex County), NJ | Princeton Junction, NJ | United States |
| Population | 47,549 | 2,208 | 329,725,481 |
| Female Population | 51.6% | 45.3% | 50.5% |
| Male Population | 48.4% | 54.7% | 49.5% |
| Median Age | 55.8 | 47.9 | 38.4 |
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| Population - 2010 | 39,418 | 2,308 | 309,327,143 |
| Population - 2000 | 27,999 | 2,382 | 285,036,114 |
| Population - 1990 | 22,255 | 2,362 | 251,960,433 |
| Pop. 2000 to Now | 60.3% | 1.6% | 15.6% |
| Pop. 1990 to Now | 101.7% | 2.5% | 30.8% |
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| Population Density | 1,132.8 | 1,211.2 | 93.4 |
| Land Area | 42.0 | 1.8 | 3,531,905.4 |
| Water Area | 0.3 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Monroe township (Middlesex County), NJ | Princeton Junction, NJ | United States |
| Age 0 to 4 | 3.2% | 6.3% | 5.9% |
| Age 5 to 9 | 5.1% | 3.3% | 6.1% |
| Age 10 to 14 | 6.3% | 6.3% | 6.6% |
| Age 15 to 17 | 3.3% | 3.3% | 3.9% |
| Age 18 to 20 | 1.3% | 0.0% | 4.0% |
| Age 21 to 24 | 2.5% | 0.9% | 5.2% |
| Age 25 to 34 | 4.4% | 16.4% | 13.8% |
| Age 35 to 44 | 10.7% | 7.2% | 12.9% |
| Age 45 to 54 | 12.4% | 14.6% | 12.6% |
| Age 55 to 59 | 6.0% | 12.5% | 6.7% |
| Age 60 to 64 | 7.2% | 12.5% | 6.3% |
| Age 65 to 74 | 18.7% | 8.2% | 9.6% |
| Age 75 to 84 | 12.5% | 6.4% | 4.5% |
| Age 85 and over | 6.4% | 2.3% | 1.9% |
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| Race | | | |
| | Monroe township (Middlesex County), NJ | Princeton Junction, NJ | United States |
| White | 68.7% | 70.2% | 59.4% |
| Black | 2.7% | 1.6% | 12.2% |
| Asian | 20.0% | 20.0% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.0% | 0.4% |
| Two or More Races | 2.2% | 4.9% | 3.2% |
| Hispanic | 6.2% | 3.4% | 18.4% |
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| Marriage & Family | | | |
| | Monroe township (Middlesex County), NJ | Princeton Junction, NJ | United States |
| Married Population | 63.7% | 72.2% | 49.8% |
| Currently Married | 63.3% | 72.2% | 48.0% |
| Married but Separated | 0.5% | 0.0% | 1.8% |
| Single Population | 36.3% | 27.8% | 50.2% |
| Never Married | 15.7% | 16.3% | 33.8% |
| Divorced | 7.7% | 7.2% | 10.8% |
| Widowed | 12.9% | 4.4% | 5.6% |
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| Household Size | 2.31 | 2.35 | 2.60 |
| Households | 20,386 | 936 | 124,010,992 |
| Family Households | 13,692 | 714 | 80,755,759 |
| Married couple, w/children | 30.6% | 36.0% | 30.5% |
| Married couple, no children | 60.2% | 57.4% | 42.9% |
| Non Family Households | 6,694 | 222 | 43,255,233 |
| Single householder, w/children | 4.9% | 2.5% | 15.8% |
| Single householder, no children | 4.3% | 4.1% | 10.8% |