| | Romulus, MI | Belleville, MI | United States |
| Population | 24,977 | 3,978 | 329,725,481 |
| Female Population | 50.7% | 58.8% | 50.5% |
| Male Population | 49.3% | 41.2% | 49.5% |
| Median Age | 35.9 | 40.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 23,937 | 3,975 | 309,327,143 |
| Population - 2000 | 22,979 | 3,997 | 285,036,114 |
| Population - 1990 | 22,897 | 3,270 | 251,960,433 |
| Pop. 2000 to Now | 2.4% | -3.3% | 15.6% |
| Pop. 1990 to Now | 2.8% | 18.2% | 30.8% |
| space4 | | | |
| Population Density | 701.4 | 3,514.1 | 93.4 |
| Land Area | 35.6 | 1.1 | 3,531,905.4 |
| Water Area | 0.3 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Romulus, MI | Belleville, MI | United States |
| Age 0 to 4 | 7.9% | 9.3% | 5.9% |
| Age 5 to 9 | 7.6% | 3.0% | 6.1% |
| Age 10 to 14 | 7.5% | 2.6% | 6.6% |
| Age 15 to 17 | 4.3% | 5.8% | 3.9% |
| Age 18 to 20 | 4.0% | 1.8% | 4.0% |
| Age 21 to 24 | 5.0% | 3.1% | 5.2% |
| Age 25 to 34 | 13.2% | 16.2% | 13.8% |
| Age 35 to 44 | 12.8% | 14.6% | 12.9% |
| Age 45 to 54 | 11.6% | 11.7% | 12.6% |
| Age 55 to 59 | 6.7% | 4.3% | 6.7% |
| Age 60 to 64 | 5.1% | 9.2% | 6.3% |
| Age 65 to 74 | 9.8% | 13.3% | 9.6% |
| Age 75 to 84 | 3.6% | 3.4% | 4.5% |
| Age 85 and over | 1.0% | 1.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Romulus, MI | Belleville, MI | United States |
| White | 48.9% | 69.0% | 59.4% |
| Black | 42.0% | 16.6% | 12.2% |
| Asian | 0.7% | 0.7% | 5.6% |
| Native American | 0.2% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.0% | 0.4% |
| Two or More Races | 5.0% | 8.0% | 3.2% |
| Hispanic | 3.1% | 5.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Romulus, MI | Belleville, MI | United States |
| Married Population | 44.9% | 44.5% | 49.8% |
| Currently Married | 42.1% | 43.3% | 48.0% |
| Married but Separated | 2.8% | 1.2% | 1.8% |
| Single Population | 55.1% | 55.5% | 50.2% |
| Never Married | 37.7% | 31.7% | 33.8% |
| Divorced | 11.6% | 16.7% | 10.8% |
| Widowed | 5.8% | 7.1% | 5.6% |
| space5 | | | |
| Household Size | 2.81 | 2.08 | 2.60 |
| Households | 8,837 | 1,900 | 124,010,992 |
| Family Households | 5,965 | 942 | 80,755,759 |
| Married couple, w/children | 23.7% | 41.1% | 30.5% |
| Married couple, no children | 38.8% | 32.9% | 42.9% |
| Non Family Households | 2,872 | 958 | 43,255,233 |
| Single householder, w/children | 25.3% | 12.7% | 15.8% |
| Single householder, no children | 12.2% | 13.3% | 10.8% |