| | Romeo, MI | Round Lake Beach, IL | United States |
| Population | 3,729 | 27,412 | 329,725,481 |
| Female Population | 53.6% | 47.1% | 50.5% |
| Male Population | 46.4% | 52.9% | 49.5% |
| Median Age | 47.6 | 33.2 | 38.4 |
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| Population - 2010 | 3,598 | 28,108 | 309,327,143 |
| Population - 2000 | 3,721 | 25,859 | 285,036,114 |
| Population - 1990 | 3,520 | 16,434 | 251,960,433 |
| Pop. 2000 to Now | -4.0% | 4.1% | 15.6% |
| Pop. 1990 to Now | 1.5% | 63.8% | 30.8% |
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| Population Density | 1,840.6 | 5,432.4 | 93.4 |
| Land Area | 2.0 | 5.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Romeo, MI | Round Lake Beach, IL | United States |
| Age 0 to 4 | 4.3% | 7.0% | 5.9% |
| Age 5 to 9 | 3.8% | 7.5% | 6.1% |
| Age 10 to 14 | 3.5% | 8.6% | 6.6% |
| Age 15 to 17 | 4.8% | 5.7% | 3.9% |
| Age 18 to 20 | 2.4% | 3.5% | 4.0% |
| Age 21 to 24 | 3.6% | 5.7% | 5.2% |
| Age 25 to 34 | 14.7% | 15.3% | 13.8% |
| Age 35 to 44 | 11.9% | 14.4% | 12.9% |
| Age 45 to 54 | 13.1% | 12.5% | 12.6% |
| Age 55 to 59 | 6.8% | 6.4% | 6.7% |
| Age 60 to 64 | 7.5% | 5.3% | 6.3% |
| Age 65 to 74 | 15.1% | 5.3% | 9.6% |
| Age 75 to 84 | 4.1% | 2.3% | 4.5% |
| Age 85 and over | 4.6% | 0.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Romeo, MI | Round Lake Beach, IL | United States |
| White | 81.4% | 39.6% | 59.4% |
| Black | 5.1% | 5.1% | 12.2% |
| Asian | 0.0% | 2.1% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 2.0% | 0.4% | 0.4% |
| Two or More Races | 2.9% | 1.9% | 3.2% |
| Hispanic | 8.6% | 50.7% | 18.4% |
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| Marriage & Family | | | |
| | Romeo, MI | Round Lake Beach, IL | United States |
| Married Population | 40.4% | 48.3% | 49.8% |
| Currently Married | 39.0% | 47.1% | 48.0% |
| Married but Separated | 1.3% | 1.3% | 1.8% |
| Single Population | 59.6% | 51.7% | 50.2% |
| Never Married | 30.0% | 37.6% | 33.8% |
| Divorced | 20.6% | 9.8% | 10.8% |
| Widowed | 9.0% | 4.3% | 5.6% |
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| Household Size | 2.00 | 3.26 | 2.60 |
| Households | 1,829 | 8,359 | 124,010,992 |
| Family Households | 962 | 6,442 | 80,755,759 |
| Married couple, w/children | 27.1% | 37.5% | 30.5% |
| Married couple, no children | 35.1% | 32.3% | 42.9% |
| Non Family Households | 867 | 1,917 | 43,255,233 |
| Single householder, w/children | 18.3% | 20.3% | 15.8% |
| Single householder, no children | 19.4% | 10.0% | 10.8% |