| | Granite City, IL | Cahokia, IL | United States |
| Population | 27,336 | 12,440 | 329,725,481 |
| Female Population | 49.2% | 53.8% | 50.5% |
| Male Population | 50.8% | 46.2% | 49.5% |
| Median Age | 39 | 31 | 38.4 |
| space3 | | | |
| Population - 2010 | 29,744 | 15,232 | 309,327,143 |
| Population - 2000 | 31,301 | 16,391 | 285,036,114 |
| Population - 1990 | 32,862 | 17,550 | 251,960,433 |
| Pop. 2000 to Now | -10.7% | -16.2% | 15.6% |
| Pop. 1990 to Now | -14.9% | -21.7% | 30.8% |
| space4 | | | |
| Population Density | 1,416.5 | 1,274.3 | 93.4 |
| Land Area | 19.3 | 9.8 | 3,531,905.4 |
| Water Area | 1.4 | 0.6 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Granite City, IL | Cahokia, IL | United States |
| Age 0 to 4 | 5.2% | 9.0% | 5.9% |
| Age 5 to 9 | 6.1% | 8.0% | 6.1% |
| Age 10 to 14 | 6.5% | 13.2% | 6.6% |
| Age 15 to 17 | 4.1% | 5.1% | 3.9% |
| Age 18 to 20 | 2.6% | 4.4% | 4.0% |
| Age 21 to 24 | 4.4% | 2.9% | 5.2% |
| Age 25 to 34 | 14.6% | 13.3% | 13.8% |
| Age 35 to 44 | 13.4% | 11.6% | 12.9% |
| Age 45 to 54 | 11.4% | 9.9% | 12.6% |
| Age 55 to 59 | 6.6% | 6.7% | 6.7% |
| Age 60 to 64 | 8.8% | 5.7% | 6.3% |
| Age 65 to 74 | 9.7% | 7.0% | 9.6% |
| Age 75 to 84 | 4.8% | 1.5% | 4.5% |
| Age 85 and over | 1.9% | 1.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Granite City, IL | Cahokia, IL | United States |
| White | 78.3% | 30.5% | 59.4% |
| Black | 10.1% | 63.2% | 12.2% |
| Asian | 0.5% | 1.3% | 5.6% |
| Native American | 0.1% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.0% | 0.4% |
| Two or More Races | 3.6% | 3.7% | 3.2% |
| Hispanic | 7.2% | 1.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Granite City, IL | Cahokia, IL | United States |
| Married Population | 43.5% | 34.0% | 49.8% |
| Currently Married | 41.1% | 28.4% | 48.0% |
| Married but Separated | 2.4% | 5.6% | 1.8% |
| Single Population | 56.5% | 66.0% | 50.2% |
| Never Married | 34.5% | 47.1% | 33.8% |
| Divorced | 15.0% | 12.7% | 10.8% |
| Widowed | 7.0% | 6.2% | 5.6% |
| space5 | | | |
| Household Size | 2.40 | 3.05 | 2.60 |
| Households | 11,291 | 4,012 | 124,010,992 |
| Family Households | 6,987 | 2,673 | 80,755,759 |
| Married couple, w/children | 21.5% | 19.3% | 30.5% |
| Married couple, no children | 40.5% | 21.8% | 42.9% |
| Non Family Households | 4,304 | 1,339 | 43,255,233 |
| Single householder, w/children | 23.9% | 38.2% | 15.8% |
| Single householder, no children | 14.1% | 20.6% | 10.8% |