| | Elgin, IL | Mundelein, IL | United States |
| Population | 114,156 | 31,596 | 329,725,481 |
| Female Population | 49.3% | 48.9% | 50.5% |
| Male Population | 50.7% | 51.2% | 49.5% |
| Median Age | 35 | 37.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 108,386 | 31,039 | 309,327,143 |
| Population - 2000 | 94,487 | 30,935 | 285,036,114 |
| Population - 1990 | 77,010 | 21,215 | 251,960,433 |
| Pop. 2000 to Now | 16.6% | 0.0% | 15.6% |
| Pop. 1990 to Now | 43.1% | 45.9% | 30.8% |
| space4 | | | |
| Population Density | 3,044.1 | 3,313.7 | 93.4 |
| Land Area | 37.5 | 9.5 | 3,531,905.4 |
| Water Area | 0.6 | 0.4 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Elgin, IL | Mundelein, IL | United States |
| Age 0 to 4 | 7.6% | 7.0% | 5.9% |
| Age 5 to 9 | 6.8% | 6.4% | 6.1% |
| Age 10 to 14 | 7.4% | 5.3% | 6.6% |
| Age 15 to 17 | 4.9% | 4.1% | 3.9% |
| Age 18 to 20 | 4.1% | 3.9% | 4.0% |
| Age 21 to 24 | 5.3% | 4.6% | 5.2% |
| Age 25 to 34 | 13.8% | 14.3% | 13.8% |
| Age 35 to 44 | 12.9% | 13.2% | 12.9% |
| Age 45 to 54 | 12.9% | 13.8% | 12.6% |
| Age 55 to 59 | 6.7% | 5.8% | 6.7% |
| Age 60 to 64 | 6.0% | 7.4% | 6.3% |
| Age 65 to 74 | 7.3% | 8.9% | 9.6% |
| Age 75 to 84 | 3.1% | 4.0% | 4.5% |
| Age 85 and over | 1.1% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Elgin, IL | Mundelein, IL | United States |
| White | 39.0% | 52.2% | 59.4% |
| Black | 5.0% | 1.3% | 12.2% |
| Asian | 5.2% | 10.6% | 5.6% |
| Native American | 0.0% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.6% | 0.4% | 0.4% |
| Two or More Races | 2.7% | 1.6% | 3.2% |
| Hispanic | 47.4% | 33.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Elgin, IL | Mundelein, IL | United States |
| Married Population | 52.0% | 55.5% | 49.8% |
| Currently Married | 50.0% | 54.9% | 48.0% |
| Married but Separated | 2.0% | 0.6% | 1.8% |
| Single Population | 48.0% | 44.5% | 50.2% |
| Never Married | 35.0% | 32.5% | 33.8% |
| Divorced | 9.3% | 8.2% | 10.8% |
| Widowed | 3.7% | 3.8% | 5.6% |
| space5 | | | |
| Household Size | 2.94 | 2.80 | 2.60 |
| Households | 38,168 | 11,178 | 124,010,992 |
| Family Households | 27,370 | 8,092 | 80,755,759 |
| Married couple, w/children | 35.8% | 35.8% | 30.5% |
| Married couple, no children | 37.0% | 46.8% | 42.9% |
| Non Family Households | 10,798 | 3,086 | 43,255,233 |
| Single householder, w/children | 16.0% | 8.8% | 15.8% |
| Single householder, no children | 11.2% | 8.6% | 10.8% |