| | Riverside, IL | Holtsville, NY | United States |
| Population | 9,346 | 19,497 | 329,725,481 |
| Female Population | 51.9% | 50.6% | 50.5% |
| Male Population | 48.1% | 49.5% | 49.5% |
| Median Age | 44.2 | 39.3 | 38.4 |
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| Population - 2010 | 8,879 | 19,277 | 309,327,143 |
| Population - 2000 | 8,895 | 17,006 | 285,036,114 |
| Population - 1990 | 8,774 | 14,972 | 251,960,433 |
| Pop. 2000 to Now | -5.0% | 17.4% | 15.6% |
| Pop. 1990 to Now | -3.6% | 33.3% | 30.8% |
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| Population Density | 4,725.0 | 2,742.6 | 93.4 |
| Land Area | 2.0 | 7.1 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Riverside, IL | Holtsville, NY | United States |
| Age 0 to 4 | 4.1% | 5.7% | 5.9% |
| Age 5 to 9 | 7.2% | 6.2% | 6.1% |
| Age 10 to 14 | 8.3% | 6.4% | 6.6% |
| Age 15 to 17 | 6.0% | 3.9% | 3.9% |
| Age 18 to 20 | 2.8% | 3.8% | 4.0% |
| Age 21 to 24 | 3.0% | 5.5% | 5.2% |
| Age 25 to 34 | 8.0% | 11.8% | 13.8% |
| Age 35 to 44 | 11.1% | 13.6% | 12.9% |
| Age 45 to 54 | 14.0% | 16.5% | 12.6% |
| Age 55 to 59 | 8.7% | 7.5% | 6.7% |
| Age 60 to 64 | 8.9% | 6.2% | 6.3% |
| Age 65 to 74 | 12.2% | 8.2% | 9.6% |
| Age 75 to 84 | 3.8% | 3.5% | 4.5% |
| Age 85 and over | 2.0% | 1.2% | 1.9% |
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| Race | | | |
| | Riverside, IL | Holtsville, NY | United States |
| White | 71.7% | 77.9% | 59.4% |
| Black | 0.7% | 5.5% | 12.2% |
| Asian | 2.1% | 3.7% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 2.1% | 0.8% | 3.2% |
| Hispanic | 23.5% | 12.0% | 18.4% |
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| Marriage & Family | | | |
| | Riverside, IL | Holtsville, NY | United States |
| Married Population | 59.8% | 54.4% | 49.8% |
| Currently Married | 58.6% | 52.8% | 48.0% |
| Married but Separated | 1.2% | 1.6% | 1.8% |
| Single Population | 40.2% | 45.6% | 50.2% |
| Never Married | 27.5% | 30.8% | 33.8% |
| Divorced | 7.8% | 10.0% | 10.8% |
| Widowed | 4.8% | 4.8% | 5.6% |
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| Household Size | 2.70 | 3.00 | 2.60 |
| Households | 3,465 | 6,474 | 124,010,992 |
| Family Households | 2,629 | 5,001 | 80,755,759 |
| Married couple, w/children | 34.8% | 34.5% | 30.5% |
| Married couple, no children | 46.3% | 40.9% | 42.9% |
| Non Family Households | 836 | 1,473 | 43,255,233 |
| Single householder, w/children | 9.8% | 11.9% | 15.8% |
| Single householder, no children | 9.2% | 12.7% | 10.8% |