| | Sun Prairie, WI | Peoria, IL | United States |
| Population | 35,528 | 113,672 | 329,725,481 |
| Female Population | 51.1% | 51.6% | 50.5% |
| Male Population | 48.9% | 48.4% | 49.5% |
| Median Age | 37.6 | 35.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 29,627 | 114,972 | 309,327,143 |
| Population - 2000 | 20,369 | 112,936 | 285,036,114 |
| Population - 1990 | 15,333 | 113,504 | 251,960,433 |
| Pop. 2000 to Now | 72.4% | -3.1% | 15.6% |
| Pop. 1990 to Now | 129.0% | -3.6% | 30.8% |
| space4 | | | |
| Population Density | 2,891.5 | 2,356.8 | 93.4 |
| Land Area | 12.3 | 48.2 | 3,531,905.4 |
| Water Area | 0.0 | 2.4 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Sun Prairie, WI | Peoria, IL | United States |
| Age 0 to 4 | 6.2% | 7.2% | 5.9% |
| Age 5 to 9 | 6.4% | 7.5% | 6.1% |
| Age 10 to 14 | 7.1% | 5.9% | 6.6% |
| Age 15 to 17 | 5.1% | 3.6% | 3.9% |
| Age 18 to 20 | 3.1% | 4.4% | 4.0% |
| Age 21 to 24 | 4.0% | 5.8% | 5.2% |
| Age 25 to 34 | 13.6% | 14.8% | 13.8% |
| Age 35 to 44 | 16.6% | 12.2% | 12.9% |
| Age 45 to 54 | 12.1% | 11.1% | 12.6% |
| Age 55 to 59 | 6.7% | 5.6% | 6.7% |
| Age 60 to 64 | 5.1% | 5.8% | 6.3% |
| Age 65 to 74 | 7.8% | 9.1% | 9.6% |
| Age 75 to 84 | 3.8% | 4.4% | 4.5% |
| Age 85 and over | 2.3% | 2.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Sun Prairie, WI | Peoria, IL | United States |
| White | 78.2% | 55.5% | 59.4% |
| Black | 7.5% | 26.7% | 12.2% |
| Asian | 5.9% | 6.4% | 5.6% |
| Native American | 0.3% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 0.0% | 0.2% |
| Other | 0.0% | 0.3% | 0.4% |
| Two or More Races | 4.2% | 4.3% | 3.2% |
| Hispanic | 3.7% | 6.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Sun Prairie, WI | Peoria, IL | United States |
| Married Population | 52.5% | 41.6% | 49.8% |
| Currently Married | 51.7% | 40.4% | 48.0% |
| Married but Separated | 0.8% | 1.2% | 1.8% |
| Single Population | 47.5% | 58.4% | 50.2% |
| Never Married | 30.6% | 40.9% | 33.8% |
| Divorced | 12.0% | 11.5% | 10.8% |
| Widowed | 4.9% | 6.0% | 5.6% |
| space5 | | | |
| Household Size | 2.41 | 2.30 | 2.60 |
| Households | 14,701 | 47,734 | 124,010,992 |
| Family Households | 9,037 | 25,855 | 80,755,759 |
| Married couple, w/children | 35.5% | 27.2% | 30.5% |
| Married couple, no children | 45.2% | 38.7% | 42.9% |
| Non Family Households | 5,664 | 21,879 | 43,255,233 |
| Single householder, w/children | 12.9% | 22.3% | 15.8% |
| Single householder, no children | 6.3% | 11.9% | 10.8% |