| | Parkville, MD | Duluth, GA | United States |
| Population | 30,783 | 31,506 | 329,725,481 |
| Female Population | 53.7% | 52.8% | 50.5% |
| Male Population | 46.3% | 47.2% | 49.5% |
| Median Age | 37.7 | 40 | 38.4 |
| space3 | | | |
| Population - 2010 | 30,156 | 26,757 | 309,327,143 |
| Population - 2000 | 31,118 | 22,122 | 285,036,114 |
| Population - 1990 | 31,617 | 9,029 | 251,960,433 |
| Pop. 2000 to Now | 1.9% | 34.2% | 15.6% |
| Pop. 1990 to Now | 0.2% | 228.7% | 30.8% |
| space4 | | | |
| Population Density | 7,183.9 | 3,083.4 | 93.4 |
| Land Area | 4.3 | 10.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Parkville, MD | Duluth, GA | United States |
| Age 0 to 4 | 6.7% | 6.4% | 5.9% |
| Age 5 to 9 | 6.2% | 5.4% | 6.1% |
| Age 10 to 14 | 5.3% | 6.8% | 6.6% |
| Age 15 to 17 | 4.1% | 3.9% | 3.9% |
| Age 18 to 20 | 3.3% | 1.9% | 4.0% |
| Age 21 to 24 | 4.8% | 4.0% | 5.2% |
| Age 25 to 34 | 15.1% | 14.2% | 13.8% |
| Age 35 to 44 | 13.2% | 15.6% | 12.9% |
| Age 45 to 54 | 13.3% | 14.7% | 12.6% |
| Age 55 to 59 | 6.6% | 6.8% | 6.7% |
| Age 60 to 64 | 7.2% | 8.4% | 6.3% |
| Age 65 to 74 | 8.6% | 6.7% | 9.6% |
| Age 75 to 84 | 3.8% | 4.0% | 4.5% |
| Age 85 and over | 1.6% | 1.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Parkville, MD | Duluth, GA | United States |
| White | 54.8% | 34.8% | 59.4% |
| Black | 36.8% | 20.4% | 12.2% |
| Asian | 2.5% | 23.6% | 5.6% |
| Native American | 0.2% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.5% | 0.1% | 0.4% |
| Two or More Races | 2.3% | 5.1% | 3.2% |
| Hispanic | 2.9% | 15.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Parkville, MD | Duluth, GA | United States |
| Married Population | 41.7% | 56.0% | 49.8% |
| Currently Married | 40.1% | 54.9% | 48.0% |
| Married but Separated | 1.6% | 1.2% | 1.8% |
| Single Population | 58.3% | 44.0% | 50.2% |
| Never Married | 40.5% | 29.0% | 33.8% |
| Divorced | 12.2% | 10.6% | 10.8% |
| Widowed | 5.6% | 4.3% | 5.6% |
| space5 | | | |
| Household Size | 2.46 | 2.55 | 2.60 |
| Households | 12,378 | 12,314 | 124,010,992 |
| Family Households | 7,741 | 8,171 | 80,755,759 |
| Married couple, w/children | 24.6% | 36.8% | 30.5% |
| Married couple, no children | 34.3% | 42.8% | 42.9% |
| Non Family Households | 4,637 | 4,143 | 43,255,233 |
| Single householder, w/children | 27.3% | 12.0% | 15.8% |
| Single householder, no children | 13.8% | 8.4% | 10.8% |