| | Oak Park, MI | Naperville, IL | United States |
| Population | 29,677 | 149,013 | 329,725,481 |
| Female Population | 53.4% | 50.5% | 50.5% |
| Male Population | 46.6% | 49.5% | 49.5% |
| Median Age | 38 | 39.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 29,423 | 142,408 | 309,327,143 |
| Population - 2000 | 29,793 | 128,358 | 285,036,114 |
| Population - 1990 | 30,462 | 85,351 | 251,960,433 |
| Pop. 2000 to Now | -1.7% | 15.3% | 15.6% |
| Pop. 1990 to Now | -3.8% | 73.4% | 30.8% |
| space4 | | | |
| Population Density | 5,756.9 | 3,839.6 | 93.4 |
| Land Area | 5.2 | 38.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.6 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Oak Park, MI | Naperville, IL | United States |
| Age 0 to 4 | 4.6% | 6.0% | 5.9% |
| Age 5 to 9 | 6.2% | 6.5% | 6.1% |
| Age 10 to 14 | 5.2% | 7.8% | 6.6% |
| Age 15 to 17 | 3.1% | 4.9% | 3.9% |
| Age 18 to 20 | 3.7% | 3.2% | 4.0% |
| Age 21 to 24 | 5.8% | 4.2% | 5.2% |
| Age 25 to 34 | 16.6% | 11.3% | 13.8% |
| Age 35 to 44 | 12.5% | 14.2% | 12.9% |
| Age 45 to 54 | 12.3% | 15.0% | 12.6% |
| Age 55 to 59 | 6.6% | 7.6% | 6.7% |
| Age 60 to 64 | 6.4% | 5.9% | 6.3% |
| Age 65 to 74 | 10.5% | 8.3% | 9.6% |
| Age 75 to 84 | 4.1% | 3.5% | 4.5% |
| Age 85 and over | 2.3% | 1.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Oak Park, MI | Naperville, IL | United States |
| White | 35.5% | 65.1% | 59.4% |
| Black | 55.4% | 4.3% | 12.2% |
| Asian | 2.5% | 20.6% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.3% | 0.0% | 0.2% |
| Other | 0.7% | 0.3% | 0.4% |
| Two or More Races | 4.3% | 3.2% | 3.2% |
| Hispanic | 1.2% | 6.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Oak Park, MI | Naperville, IL | United States |
| Married Population | 37.3% | 61.8% | 49.8% |
| Currently Married | 35.6% | 60.9% | 48.0% |
| Married but Separated | 1.7% | 0.9% | 1.8% |
| Single Population | 62.7% | 38.2% | 50.2% |
| Never Married | 43.3% | 27.2% | 33.8% |
| Divorced | 13.5% | 7.0% | 10.8% |
| Widowed | 5.8% | 4.0% | 5.6% |
| space5 | | | |
| Household Size | 2.42 | 2.75 | 2.60 |
| Households | 12,262 | 53,234 | 124,010,992 |
| Family Households | 6,938 | 39,815 | 80,755,759 |
| Married couple, w/children | 20.5% | 42.3% | 30.5% |
| Married couple, no children | 36.6% | 43.9% | 42.9% |
| Non Family Households | 5,324 | 13,419 | 43,255,233 |
| Single householder, w/children | 19.0% | 8.4% | 15.8% |
| Single householder, no children | 23.9% | 5.3% | 10.8% |