| | Sullivan, IL | Russellville, AL | United States |
| Population | 4,532 | 10,691 | 329,725,481 |
| Female Population | 53.0% | 52.0% | 50.5% |
| Male Population | 47.0% | 48.1% | 49.5% |
| Median Age | 38.4 | 32.5 | 38.4 |
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| Population - 2010 | 4,453 | 9,834 | 309,327,143 |
| Population - 2000 | 4,326 | 8,971 | 285,036,114 |
| Population - 1990 | 4,354 | 7,812 | 251,960,433 |
| Pop. 2000 to Now | 1.7% | 8.8% | 15.6% |
| Pop. 1990 to Now | 1.1% | 24.9% | 30.8% |
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| Population Density | 1,667.4 | 797.5 | 93.4 |
| Land Area | 2.7 | 13.4 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Sullivan, IL | Russellville, AL | United States |
| Age 0 to 4 | 6.0% | 9.0% | 5.9% |
| Age 5 to 9 | 6.4% | 6.4% | 6.1% |
| Age 10 to 14 | 9.8% | 9.0% | 6.6% |
| Age 15 to 17 | 4.3% | 4.2% | 3.9% |
| Age 18 to 20 | 3.3% | 6.0% | 4.0% |
| Age 21 to 24 | 3.2% | 4.5% | 5.2% |
| Age 25 to 34 | 12.6% | 14.0% | 13.8% |
| Age 35 to 44 | 12.8% | 12.9% | 12.9% |
| Age 45 to 54 | 12.0% | 9.2% | 12.6% |
| Age 55 to 59 | 7.0% | 4.0% | 6.7% |
| Age 60 to 64 | 4.6% | 6.5% | 6.3% |
| Age 65 to 74 | 9.9% | 7.7% | 9.6% |
| Age 75 to 84 | 5.7% | 4.4% | 4.5% |
| Age 85 and over | 2.4% | 2.2% | 1.9% |
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| Race | | | |
| | Sullivan, IL | Russellville, AL | United States |
| White | 95.4% | 49.4% | 59.4% |
| Black | 2.0% | 9.2% | 12.2% |
| Asian | 0.3% | 0.2% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.8% | 1.2% | 3.2% |
| Hispanic | 1.4% | 39.9% | 18.4% |
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| Marriage & Family | | | |
| | Sullivan, IL | Russellville, AL | United States |
| Married Population | 52.4% | 46.7% | 49.8% |
| Currently Married | 50.0% | 44.3% | 48.0% |
| Married but Separated | 2.4% | 2.4% | 1.8% |
| Single Population | 47.6% | 53.3% | 50.2% |
| Never Married | 23.2% | 34.6% | 33.8% |
| Divorced | 14.8% | 13.2% | 10.8% |
| Widowed | 9.6% | 5.5% | 5.6% |
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| Household Size | 2.46 | 3.09 | 2.60 |
| Households | 1,760 | 3,400 | 124,010,992 |
| Family Households | 1,196 | 2,152 | 80,755,759 |
| Married couple, w/children | 22.4% | 28.3% | 30.5% |
| Married couple, no children | 48.1% | 34.7% | 42.9% |
| Non Family Households | 564 | 1,248 | 43,255,233 |
| Single householder, w/children | 23.2% | 27.8% | 15.8% |
| Single householder, no children | 6.3% | 9.1% | 10.8% |