| | Mount Prospect, IL | Gardena, CA | United States |
| Population | 56,510 | 60,917 | 329,725,481 |
| Female Population | 50.2% | 52.1% | 50.5% |
| Male Population | 49.9% | 47.9% | 49.5% |
| Median Age | 40.5 | 40 | 38.4 |
| space3 | | | |
| Population - 2010 | 55,082 | 58,828 | 309,327,143 |
| Population - 2000 | 56,265 | 57,746 | 285,036,114 |
| Population - 1990 | 53,170 | 49,847 | 251,960,433 |
| Pop. 2000 to Now | -5.3% | 1.3% | 15.6% |
| Pop. 1990 to Now | 0.2% | 17.4% | 30.8% |
| space4 | | | |
| Population Density | 5,272.0 | 10,450.7 | 93.4 |
| Land Area | 10.7 | 5.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Mount Prospect, IL | Gardena, CA | United States |
| Age 0 to 4 | 6.9% | 5.1% | 5.9% |
| Age 5 to 9 | 5.5% | 6.5% | 6.1% |
| Age 10 to 14 | 6.6% | 5.3% | 6.6% |
| Age 15 to 17 | 3.9% | 2.9% | 3.9% |
| Age 18 to 20 | 2.5% | 3.3% | 4.0% |
| Age 21 to 24 | 2.9% | 4.4% | 5.2% |
| Age 25 to 34 | 13.4% | 15.6% | 13.8% |
| Age 35 to 44 | 14.0% | 13.4% | 12.9% |
| Age 45 to 54 | 14.6% | 13.5% | 12.6% |
| Age 55 to 59 | 5.9% | 6.6% | 6.7% |
| Age 60 to 64 | 6.1% | 7.3% | 6.3% |
| Age 65 to 74 | 9.3% | 9.4% | 9.6% |
| Age 75 to 84 | 5.9% | 4.7% | 4.5% |
| Age 85 and over | 2.5% | 2.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Mount Prospect, IL | Gardena, CA | United States |
| White | 64.5% | 8.7% | 59.4% |
| Black | 3.1% | 19.0% | 12.2% |
| Asian | 13.7% | 25.3% | 5.6% |
| Native American | 0.2% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.2% | 1.1% | 0.4% |
| Two or More Races | 2.2% | 2.8% | 3.2% |
| Hispanic | 16.0% | 42.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Mount Prospect, IL | Gardena, CA | United States |
| Married Population | 60.6% | 46.4% | 49.8% |
| Currently Married | 59.4% | 43.3% | 48.0% |
| Married but Separated | 1.1% | 3.1% | 1.8% |
| Single Population | 39.4% | 53.6% | 50.2% |
| Never Married | 26.2% | 39.4% | 33.8% |
| Divorced | 7.0% | 9.1% | 10.8% |
| Widowed | 6.2% | 5.2% | 5.6% |
| space5 | | | |
| Household Size | 2.60 | 2.89 | 2.60 |
| Households | 21,666 | 20,806 | 124,010,992 |
| Family Households | 15,235 | 14,131 | 80,755,759 |
| Married couple, w/children | 38.6% | 29.2% | 30.5% |
| Married couple, no children | 44.8% | 36.5% | 42.9% |
| Non Family Households | 6,431 | 6,675 | 43,255,233 |
| Single householder, w/children | 8.3% | 16.0% | 15.8% |
| Single householder, no children | 8.3% | 18.3% | 10.8% |