| | Brookfield, IL | Gallatin, TN | United States |
| Population | 19,517 | 43,306 | 329,725,481 |
| Female Population | 53.8% | 50.1% | 50.5% |
| Male Population | 46.2% | 49.9% | 49.5% |
| Median Age | 40.2 | 38.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 18,982 | 30,514 | 309,327,143 |
| Population - 2000 | 19,085 | 23,230 | 285,036,114 |
| Population - 1990 | 18,876 | 18,794 | 251,960,433 |
| Pop. 2000 to Now | -5.2% | 90.9% | 15.6% |
| Pop. 1990 to Now | -4.2% | 135.9% | 30.8% |
| space4 | | | |
| Population Density | 6,371.9 | 1,363.0 | 93.4 |
| Land Area | 3.1 | 31.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.6 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Brookfield, IL | Gallatin, TN | United States |
| Age 0 to 4 | 6.6% | 5.8% | 5.9% |
| Age 5 to 9 | 7.9% | 8.0% | 6.1% |
| Age 10 to 14 | 6.5% | 6.0% | 6.6% |
| Age 15 to 17 | 4.3% | 2.9% | 3.9% |
| Age 18 to 20 | 2.5% | 3.7% | 4.0% |
| Age 21 to 24 | 2.6% | 4.4% | 5.2% |
| Age 25 to 34 | 9.1% | 14.5% | 13.8% |
| Age 35 to 44 | 17.4% | 13.1% | 12.9% |
| Age 45 to 54 | 15.5% | 13.6% | 12.6% |
| Age 55 to 59 | 7.4% | 6.5% | 6.7% |
| Age 60 to 64 | 7.4% | 5.3% | 6.3% |
| Age 65 to 74 | 7.6% | 9.0% | 9.6% |
| Age 75 to 84 | 3.6% | 5.5% | 4.5% |
| Age 85 and over | 1.7% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Brookfield, IL | Gallatin, TN | United States |
| White | 71.5% | 69.9% | 59.4% |
| Black | 3.7% | 13.9% | 12.2% |
| Asian | 1.2% | 2.8% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.2% | 0.4% |
| Two or More Races | 2.9% | 4.6% | 3.2% |
| Hispanic | 20.5% | 8.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Brookfield, IL | Gallatin, TN | United States |
| Married Population | 54.7% | 52.0% | 49.8% |
| Currently Married | 53.4% | 51.2% | 48.0% |
| Married but Separated | 1.3% | 0.8% | 1.8% |
| Single Population | 45.3% | 48.0% | 50.2% |
| Never Married | 29.6% | 29.0% | 33.8% |
| Divorced | 10.6% | 13.0% | 10.8% |
| Widowed | 5.0% | 6.0% | 5.6% |
| space5 | | | |
| Household Size | 2.55 | 2.47 | 2.60 |
| Households | 7,590 | 17,127 | 124,010,992 |
| Family Households | 5,005 | 11,622 | 80,755,759 |
| Married couple, w/children | 39.2% | 26.9% | 30.5% |
| Married couple, no children | 41.4% | 45.1% | 42.9% |
| Non Family Households | 2,585 | 5,505 | 43,255,233 |
| Single householder, w/children | 11.1% | 17.7% | 15.8% |
| Single householder, no children | 8.3% | 10.2% | 10.8% |