| | Dardenne Prairie, MO | Lake St. Louis, MO | United States |
| Population | 12,689 | 16,665 | 329,725,481 |
| Female Population | 49.4% | 49.2% | 50.5% |
| Male Population | 50.6% | 50.8% | 49.5% |
| Median Age | 44 | 43.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 11,676 | 14,607 | 309,327,143 |
| Population - 2000 | 4,384 | 10,169 | 285,036,114 |
| Population - 1990 | 1,769 | 8,355 | 251,960,433 |
| Pop. 2000 to Now | 205.6% | 69.0% | 15.6% |
| Pop. 1990 to Now | 657.3% | 105.7% | 30.8% |
| space4 | | | |
| Population Density | 2,452.9 | 2,002.5 | 93.4 |
| Land Area | 5.2 | 8.3 | 3,531,905.4 |
| Water Area | 0.0 | 0.8 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Dardenne Prairie, MO | Lake St. Louis, MO | United States |
| Age 0 to 4 | 4.1% | 3.4% | 5.9% |
| Age 5 to 9 | 5.6% | 7.4% | 6.1% |
| Age 10 to 14 | 9.9% | 5.0% | 6.6% |
| Age 15 to 17 | 7.0% | 4.6% | 3.9% |
| Age 18 to 20 | 2.9% | 2.6% | 4.0% |
| Age 21 to 24 | 3.0% | 6.9% | 5.2% |
| Age 25 to 34 | 5.8% | 8.6% | 13.8% |
| Age 35 to 44 | 13.7% | 12.9% | 12.9% |
| Age 45 to 54 | 18.0% | 13.3% | 12.6% |
| Age 55 to 59 | 8.6% | 6.9% | 6.7% |
| Age 60 to 64 | 6.9% | 8.2% | 6.3% |
| Age 65 to 74 | 9.5% | 10.7% | 9.6% |
| Age 75 to 84 | 4.1% | 7.1% | 4.5% |
| Age 85 and over | 0.9% | 2.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Dardenne Prairie, MO | Lake St. Louis, MO | United States |
| White | 88.4% | 86.6% | 59.4% |
| Black | 3.9% | 4.2% | 12.2% |
| Asian | 2.6% | 1.3% | 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 | 2.0% | 3.5% | 3.2% |
| Hispanic | 3.1% | 4.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Dardenne Prairie, MO | Lake St. Louis, MO | United States |
| Married Population | 68.2% | 63.1% | 49.8% |
| Currently Married | 67.3% | 62.8% | 48.0% |
| Married but Separated | 0.8% | 0.3% | 1.8% |
| Single Population | 31.8% | 36.9% | 50.2% |
| Never Married | 21.1% | 22.6% | 33.8% |
| Divorced | 7.1% | 10.3% | 10.8% |
| Widowed | 3.6% | 4.0% | 5.6% |
| space5 | | | |
| Household Size | 2.85 | 2.47 | 2.60 |
| Households | 4,459 | 6,747 | 124,010,992 |
| Family Households | 3,713 | 4,878 | 80,755,759 |
| Married couple, w/children | 42.5% | 34.6% | 30.5% |
| Married couple, no children | 48.9% | 55.5% | 42.9% |
| Non Family Households | 746 | 1,869 | 43,255,233 |
| Single householder, w/children | 3.5% | 6.9% | 15.8% |
| Single householder, no children | 5.0% | 3.0% | 10.8% |