| | Kirkwood, MO | Highland, IL | United States |
| Population | 29,233 | 10,215 | 329,725,481 |
| Female Population | 52.5% | 50.8% | 50.5% |
| Male Population | 47.5% | 49.2% | 49.5% |
| Median Age | 41.4 | 40.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 27,558 | 9,967 | 309,327,143 |
| Population - 2000 | 27,324 | 8,438 | 285,036,114 |
| Population - 1990 | 27,291 | 7,525 | 251,960,433 |
| Pop. 2000 to Now | 2.0% | 18.7% | 15.6% |
| Pop. 1990 to Now | 2.1% | 33.1% | 30.8% |
| space4 | | | |
| Population Density | 3,197.0 | 1,524.2 | 93.4 |
| Land Area | 9.1 | 6.7 | 3,531,905.4 |
| Water Area | 0.0 | 1.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Kirkwood, MO | Highland, IL | United States |
| Age 0 to 4 | 5.9% | 6.5% | 5.9% |
| Age 5 to 9 | 6.2% | 6.0% | 6.1% |
| Age 10 to 14 | 8.4% | 5.3% | 6.6% |
| Age 15 to 17 | 5.7% | 2.7% | 3.9% |
| Age 18 to 20 | 2.2% | 1.1% | 4.0% |
| Age 21 to 24 | 3.7% | 5.2% | 5.2% |
| Age 25 to 34 | 9.7% | 15.6% | 13.8% |
| Age 35 to 44 | 12.5% | 13.0% | 12.9% |
| Age 45 to 54 | 12.6% | 10.0% | 12.6% |
| Age 55 to 59 | 6.3% | 7.0% | 6.7% |
| Age 60 to 64 | 6.4% | 9.2% | 6.3% |
| Age 65 to 74 | 12.5% | 9.4% | 9.6% |
| Age 75 to 84 | 5.0% | 5.6% | 4.5% |
| Age 85 and over | 3.0% | 3.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Kirkwood, MO | Highland, IL | United States |
| White | 84.2% | 91.0% | 59.4% |
| Black | 5.3% | 3.0% | 12.2% |
| Asian | 1.3% | 2.4% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.5% | 0.0% | 0.4% |
| Two or More Races | 5.7% | 1.1% | 3.2% |
| Hispanic | 3.0% | 2.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Kirkwood, MO | Highland, IL | United States |
| Married Population | 57.4% | 53.8% | 49.8% |
| Currently Married | 55.8% | 50.5% | 48.0% |
| Married but Separated | 1.5% | 3.3% | 1.8% |
| Single Population | 42.6% | 46.2% | 50.2% |
| Never Married | 26.8% | 25.1% | 33.8% |
| Divorced | 9.7% | 12.6% | 10.8% |
| Widowed | 6.1% | 8.4% | 5.6% |
| space5 | | | |
| Household Size | 2.40 | 2.21 | 2.60 |
| Households | 12,077 | 4,553 | 124,010,992 |
| Family Households | 7,617 | 2,763 | 80,755,759 |
| Married couple, w/children | 39.2% | 27.9% | 30.5% |
| Married couple, no children | 44.0% | 46.4% | 42.9% |
| Non Family Households | 4,460 | 1,790 | 43,255,233 |
| Single householder, w/children | 9.8% | 18.5% | 15.8% |
| Single householder, no children | 7.0% | 7.3% | 10.8% |