| | Hillside, NJ | Middletown, NY | United States |
| Population | 22,319 | 30,086 | 329,725,481 |
| Female Population | 51.4% | 50.2% | 50.5% |
| Male Population | 48.6% | 49.8% | 49.5% |
| Median Age | 36.9 | 37.8 | 38.4 |
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| Population - 2010 | 21,494 | 28,153 | 309,327,143 |
| Population - 2000 | 21,747 | 25,388 | 285,036,114 |
| Population - 1990 | 21,044 | 24,160 | 251,960,433 |
| Pop. 2000 to Now | 0.4% | 10.4% | 15.6% |
| Pop. 1990 to Now | 3.8% | 16.0% | 30.8% |
| space4 | | | |
| Population Density | 8,119.0 | 5,927.1 | 93.4 |
| Land Area | 2.7 | 5.1 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Hillside, NJ | Middletown, NY | United States |
| Age 0 to 4 | 6.0% | 6.7% | 5.9% |
| Age 5 to 9 | 6.4% | 6.6% | 6.1% |
| Age 10 to 14 | 6.0% | 7.7% | 6.6% |
| Age 15 to 17 | 3.5% | 3.9% | 3.9% |
| Age 18 to 20 | 4.3% | 3.4% | 4.0% |
| Age 21 to 24 | 5.7% | 5.0% | 5.2% |
| Age 25 to 34 | 16.5% | 12.8% | 13.8% |
| Age 35 to 44 | 10.2% | 12.2% | 12.9% |
| Age 45 to 54 | 14.6% | 12.7% | 12.6% |
| Age 55 to 59 | 8.1% | 7.5% | 6.7% |
| Age 60 to 64 | 6.0% | 5.6% | 6.3% |
| Age 65 to 74 | 7.6% | 10.0% | 9.6% |
| Age 75 to 84 | 4.0% | 4.3% | 4.5% |
| Age 85 and over | 1.3% | 1.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Hillside, NJ | Middletown, NY | United States |
| White | 19.9% | 34.2% | 59.4% |
| Black | 49.3% | 19.4% | 12.2% |
| Asian | 2.0% | 3.8% | 5.6% |
| Native American | 0.4% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 3.8% | 3.6% | 0.4% |
| Two or More Races | 1.6% | 2.0% | 3.2% |
| Hispanic | 23.2% | 36.9% | 18.4% |
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| Marriage & Family | | | |
| | Hillside, NJ | Middletown, NY | United States |
| Married Population | 43.7% | 46.5% | 49.8% |
| Currently Married | 41.2% | 44.9% | 48.0% |
| Married but Separated | 2.5% | 1.7% | 1.8% |
| Single Population | 56.3% | 53.5% | 50.2% |
| Never Married | 40.6% | 39.2% | 33.8% |
| Divorced | 8.9% | 9.1% | 10.8% |
| Widowed | 6.8% | 5.2% | 5.6% |
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| Household Size | 3.10 | 2.80 | 2.60 |
| Households | 7,191 | 10,604 | 124,010,992 |
| Family Households | 5,512 | 6,681 | 80,755,759 |
| Married couple, w/children | 25.3% | 32.2% | 30.5% |
| Married couple, no children | 33.9% | 38.0% | 42.9% |
| Non Family Households | 1,679 | 3,923 | 43,255,233 |
| Single householder, w/children | 21.3% | 19.7% | 15.8% |
| Single householder, no children | 19.5% | 10.1% | 10.8% |