| | Macomb, IL | Carthage, IL | United States |
| Population | 15,681 | 2,554 | 329,725,481 |
| Female Population | 53.8% | 47.5% | 50.5% |
| Male Population | 46.2% | 52.6% | 49.5% |
| Median Age | 26.8 | 44.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 19,310 | 2,605 | 309,327,143 |
| Population - 2000 | 18,558 | 2,725 | 285,036,114 |
| Population - 1990 | 19,952 | 2,657 | 251,960,433 |
| Pop. 2000 to Now | -7.3% | -11.2% | 15.6% |
| Pop. 1990 to Now | -13.8% | -9.0% | 30.8% |
| space4 | | | |
| Population Density | 1,439.4 | 1,051.9 | 93.4 |
| Land Area | 10.9 | 2.4 | 3,531,905.4 |
| Water Area | 0.4 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Macomb, IL | Carthage, IL | United States |
| Age 0 to 4 | 3.0% | 3.6% | 5.9% |
| Age 5 to 9 | 3.6% | 4.1% | 6.1% |
| Age 10 to 14 | 5.2% | 6.5% | 6.6% |
| Age 15 to 17 | 2.5% | 2.2% | 3.9% |
| Age 18 to 20 | 17.5% | 0.8% | 4.0% |
| Age 21 to 24 | 15.4% | 6.2% | 5.2% |
| Age 25 to 34 | 11.8% | 15.7% | 13.8% |
| Age 35 to 44 | 9.4% | 12.5% | 12.9% |
| Age 45 to 54 | 6.7% | 9.1% | 12.6% |
| Age 55 to 59 | 4.0% | 10.4% | 6.7% |
| Age 60 to 64 | 5.0% | 6.3% | 6.3% |
| Age 65 to 74 | 8.2% | 7.2% | 9.6% |
| Age 75 to 84 | 3.9% | 10.8% | 4.5% |
| Age 85 and over | 3.8% | 4.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Macomb, IL | Carthage, IL | United States |
| White | 81.2% | 92.0% | 59.4% |
| Black | 8.3% | 0.6% | 12.2% |
| Asian | 3.4% | 0.2% | 5.6% |
| Native American | 0.1% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.5% | 2.9% | 3.2% |
| Hispanic | 4.5% | 4.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Macomb, IL | Carthage, IL | United States |
| Married Population | 30.2% | 56.5% | 49.8% |
| Currently Married | 28.7% | 54.6% | 48.0% |
| Married but Separated | 1.4% | 1.9% | 1.8% |
| Single Population | 69.8% | 43.5% | 50.2% |
| Never Married | 53.2% | 19.0% | 33.8% |
| Divorced | 9.3% | 14.6% | 10.8% |
| Widowed | 7.4% | 9.9% | 5.6% |
| space5 | | | |
| Household Size | 2.11 | 2.04 | 2.60 |
| Households | 6,017 | 1,220 | 124,010,992 |
| Family Households | 2,316 | 716 | 80,755,759 |
| Married couple, w/children | 31.6% | 22.5% | 30.5% |
| Married couple, no children | 44.8% | 62.3% | 42.9% |
| Non Family Households | 3,701 | 504 | 43,255,233 |
| Single householder, w/children | 14.3% | 4.9% | 15.8% |
| Single householder, no children | 9.2% | 10.3% | 10.8% |