| | Sussex, WI | Sterling, CO | United States |
| Population | 11,398 | 13,976 | 329,725,481 |
| Female Population | 51.4% | 43.4% | 50.5% |
| Male Population | 48.6% | 56.6% | 49.5% |
| Median Age | 37.7 | 37 | 38.4 |
| space3 | | | |
| Population - 2010 | 10,529 | 14,828 | 309,327,143 |
| Population - 2000 | 8,828 | 11,360 | 285,036,114 |
| Population - 1990 | 5,039 | 10,362 | 251,960,433 |
| Pop. 2000 to Now | 25.6% | 23.9% | 15.6% |
| Pop. 1990 to Now | 120.0% | 35.9% | 30.8% |
| space4 | | | |
| Population Density | 1,461.1 | 1,835.3 | 93.4 |
| Land Area | 7.8 | 7.6 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Sussex, WI | Sterling, CO | United States |
| Age 0 to 4 | 4.7% | 6.5% | 5.9% |
| Age 5 to 9 | 7.5% | 4.9% | 6.1% |
| Age 10 to 14 | 9.2% | 5.0% | 6.6% |
| Age 15 to 17 | 5.1% | 3.1% | 3.9% |
| Age 18 to 20 | 2.2% | 5.7% | 4.0% |
| Age 21 to 24 | 4.9% | 4.9% | 5.2% |
| Age 25 to 34 | 13.4% | 17.0% | 13.8% |
| Age 35 to 44 | 12.7% | 13.5% | 12.9% |
| Age 45 to 54 | 14.6% | 12.4% | 12.6% |
| Age 55 to 59 | 7.8% | 3.8% | 6.7% |
| Age 60 to 64 | 5.9% | 5.6% | 6.3% |
| Age 65 to 74 | 6.6% | 9.6% | 9.6% |
| Age 75 to 84 | 4.3% | 5.3% | 4.5% |
| Age 85 and over | 1.1% | 2.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Sussex, WI | Sterling, CO | United States |
| White | 88.8% | 70.0% | 59.4% |
| Black | 0.3% | 1.4% | 12.2% |
| Asian | 7.8% | 0.4% | 5.6% |
| Native American | 0.0% | 0.8% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 1.4% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 0.9% | 5.2% | 3.2% |
| Hispanic | 2.1% | 20.7% | 18.4% |
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| Marriage & Family | | | |
| | Sussex, WI | Sterling, CO | United States |
| Married Population | 57.6% | 42.3% | 49.8% |
| Currently Married | 56.9% | 40.9% | 48.0% |
| Married but Separated | 0.7% | 1.3% | 1.8% |
| Single Population | 42.4% | 57.7% | 50.2% |
| Never Married | 27.7% | 33.6% | 33.8% |
| Divorced | 10.3% | 17.4% | 10.8% |
| Widowed | 4.4% | 6.7% | 5.6% |
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| Household Size | 2.60 | 2.59 | 2.60 |
| Households | 4,383 | 5,050 | 124,010,992 |
| Family Households | 2,978 | 2,609 | 80,755,759 |
| Married couple, w/children | 38.1% | 36.0% | 30.5% |
| Married couple, no children | 41.5% | 36.8% | 42.9% |
| Non Family Households | 1,405 | 2,441 | 43,255,233 |
| Single householder, w/children | 12.6% | 15.0% | 15.8% |
| Single householder, no children | 7.8% | 12.2% | 10.8% |