| | Willowbrook, IL | Conroe, TX | United States |
| Population | 9,178 | 87,930 | 329,725,481 |
| Female Population | 55.4% | 49.6% | 50.5% |
| Male Population | 44.6% | 50.4% | 49.5% |
| Median Age | 48.8 | 32.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 8,685 | 65,712 | 309,327,143 |
| Population - 2000 | 8,967 | 36,811 | 285,036,114 |
| Population - 1990 | 8,598 | 27,610 | 251,960,433 |
| Pop. 2000 to Now | -5.1% | 161.4% | 15.6% |
| Pop. 1990 to Now | -1.1% | 248.5% | 30.8% |
| space4 | | | |
| Population Density | 3,410.6 | 1,252.9 | 93.4 |
| Land Area | 2.7 | 70.2 | 3,531,905.4 |
| Water Area | 0.1 | 0.8 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Willowbrook, IL | Conroe, TX | United States |
| Age 0 to 4 | 5.9% | 6.9% | 5.9% |
| Age 5 to 9 | 4.2% | 6.6% | 6.1% |
| Age 10 to 14 | 3.4% | 7.7% | 6.6% |
| Age 15 to 17 | 3.2% | 3.7% | 3.9% |
| Age 18 to 20 | 3.1% | 3.6% | 4.0% |
| Age 21 to 24 | 2.9% | 7.7% | 5.2% |
| Age 25 to 34 | 12.4% | 16.6% | 13.8% |
| Age 35 to 44 | 11.2% | 12.8% | 12.9% |
| Age 45 to 54 | 12.1% | 11.0% | 12.6% |
| Age 55 to 59 | 8.2% | 5.3% | 6.7% |
| Age 60 to 64 | 8.1% | 4.6% | 6.3% |
| Age 65 to 74 | 11.7% | 7.7% | 9.6% |
| Age 75 to 84 | 8.7% | 4.0% | 4.5% |
| Age 85 and over | 4.8% | 1.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Willowbrook, IL | Conroe, TX | United States |
| White | 75.6% | 52.9% | 59.4% |
| Black | 3.4% | 11.8% | 12.2% |
| Asian | 13.4% | 2.9% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.1% | 0.1% | 0.4% |
| Two or More Races | 1.0% | 1.9% | 3.2% |
| Hispanic | 6.4% | 30.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Willowbrook, IL | Conroe, TX | United States |
| Married Population | 57.3% | 52.6% | 49.8% |
| Currently Married | 56.9% | 50.3% | 48.0% |
| Married but Separated | 0.4% | 2.3% | 1.8% |
| Single Population | 42.7% | 47.4% | 50.2% |
| Never Married | 25.9% | 32.5% | 33.8% |
| Divorced | 9.8% | 9.5% | 10.8% |
| Widowed | 6.9% | 5.3% | 5.6% |
| space5 | | | |
| Household Size | 2.21 | 2.64 | 2.60 |
| Households | 4,103 | 32,775 | 124,010,992 |
| Family Households | 2,574 | 21,497 | 80,755,759 |
| Married couple, w/children | 24.3% | 36.8% | 30.5% |
| Married couple, no children | 60.4% | 38.8% | 42.9% |
| Non Family Households | 1,529 | 11,278 | 43,255,233 |
| Single householder, w/children | 9.1% | 15.0% | 15.8% |
| Single householder, no children | 6.3% | 9.3% | 10.8% |