| | Brookhaven, PA | Mount Vernon, IA | United States |
| Population | 8,243 | 4,498 | 329,725,481 |
| Female Population | 46.3% | 50.9% | 50.5% |
| Male Population | 53.7% | 49.1% | 49.5% |
| Median Age | 44.4 | 22.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 8,023 | 4,509 | 309,327,143 |
| Population - 2000 | 7,985 | 3,390 | 285,036,114 |
| Population - 1990 | 8,567 | 3,657 | 251,960,433 |
| Pop. 2000 to Now | 0.9% | 33.6% | 15.6% |
| Pop. 1990 to Now | -6.0% | 23.8% | 30.8% |
| space4 | | | |
| Population Density | 4,826.1 | 1,287.7 | 93.4 |
| Land Area | 1.7 | 3.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Brookhaven, PA | Mount Vernon, IA | United States |
| Age 0 to 4 | 6.6% | 2.4% | 5.9% |
| Age 5 to 9 | 4.1% | 2.4% | 6.1% |
| Age 10 to 14 | 7.4% | 12.5% | 6.6% |
| Age 15 to 17 | 2.3% | 7.8% | 3.9% |
| Age 18 to 20 | 2.2% | 20.0% | 4.0% |
| Age 21 to 24 | 3.2% | 6.7% | 5.2% |
| Age 25 to 34 | 14.6% | 5.2% | 13.8% |
| Age 35 to 44 | 10.0% | 13.3% | 12.9% |
| Age 45 to 54 | 13.3% | 8.7% | 12.6% |
| Age 55 to 59 | 11.3% | 6.6% | 6.7% |
| Age 60 to 64 | 7.3% | 5.2% | 6.3% |
| Age 65 to 74 | 9.1% | 3.3% | 9.6% |
| Age 75 to 84 | 5.1% | 4.8% | 4.5% |
| Age 85 and over | 3.5% | 1.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Brookhaven, PA | Mount Vernon, IA | United States |
| White | 88.0% | 93.2% | 59.4% |
| Black | 7.0% | 1.0% | 12.2% |
| Asian | 0.7% | 1.8% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.8% | 0.4% |
| Two or More Races | 2.8% | 1.9% | 3.2% |
| Hispanic | 1.5% | 1.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Brookhaven, PA | Mount Vernon, IA | United States |
| Married Population | 47.3% | 39.5% | 49.8% |
| Currently Married | 45.6% | 39.4% | 48.0% |
| Married but Separated | 1.7% | 0.1% | 1.8% |
| Single Population | 52.7% | 60.5% | 50.2% |
| Never Married | 32.0% | 52.9% | 33.8% |
| Divorced | 13.6% | 3.6% | 10.8% |
| Widowed | 7.1% | 4.1% | 5.6% |
| space5 | | | |
| Household Size | 2.27 | 2.70 | 2.60 |
| Households | 3,617 | 1,271 | 124,010,992 |
| Family Households | 2,196 | 905 | 80,755,759 |
| Married couple, w/children | 29.3% | 43.9% | 30.5% |
| Married couple, no children | 39.6% | 36.5% | 42.9% |
| Non Family Households | 1,421 | 366 | 43,255,233 |
| Single householder, w/children | 24.4% | 14.9% | 15.8% |
| Single householder, no children | 6.7% | 4.8% | 10.8% |