| | Federalsburg, MD | Seaford, DE | United States |
| Population | 2,824 | 7,852 | 329,725,481 |
| Female Population | 57.7% | 52.8% | 50.5% |
| Male Population | 42.4% | 47.2% | 49.5% |
| Median Age | 32.1 | 41.8 | 38.4 |
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| Population - 2010 | 2,735 | 6,916 | 309,327,143 |
| Population - 2000 | 2,620 | 6,699 | 285,036,114 |
| Population - 1990 | 2,365 | 5,689 | 251,960,433 |
| Pop. 2000 to Now | 1.5% | 23.1% | 15.6% |
| Pop. 1990 to Now | 12.4% | 45.0% | 30.8% |
| space4 | | | |
| Population Density | 1,463.2 | 1,499.3 | 93.4 |
| Land Area | 1.9 | 5.2 | 3,531,905.4 |
| Water Area | 0.1 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Federalsburg, MD | Seaford, DE | United States |
| Age 0 to 4 | 7.9% | 7.7% | 5.9% |
| Age 5 to 9 | 9.4% | 5.9% | 6.1% |
| Age 10 to 14 | 10.2% | 5.4% | 6.6% |
| Age 15 to 17 | 3.4% | 2.6% | 3.9% |
| Age 18 to 20 | 5.4% | 5.1% | 4.0% |
| Age 21 to 24 | 4.1% | 5.2% | 5.2% |
| Age 25 to 34 | 13.3% | 10.1% | 13.8% |
| Age 35 to 44 | 10.4% | 11.9% | 12.9% |
| Age 45 to 54 | 9.8% | 14.5% | 12.6% |
| Age 55 to 59 | 6.0% | 6.4% | 6.7% |
| Age 60 to 64 | 5.7% | 6.3% | 6.3% |
| Age 65 to 74 | 8.7% | 11.4% | 9.6% |
| Age 75 to 84 | 3.2% | 4.4% | 4.5% |
| Age 85 and over | 2.5% | 3.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Federalsburg, MD | Seaford, DE | United States |
| White | 43.4% | 53.8% | 59.4% |
| Black | 42.3% | 29.3% | 12.2% |
| Asian | 0.0% | 2.8% | 5.6% |
| Native American | 0.3% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 7.3% | 5.2% | 3.2% |
| Hispanic | 6.7% | 8.8% | 18.4% |
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| Marriage & Family | | | |
| | Federalsburg, MD | Seaford, DE | United States |
| Married Population | 36.2% | 41.6% | 49.8% |
| Currently Married | 33.4% | 40.1% | 48.0% |
| Married but Separated | 2.7% | 1.5% | 1.8% |
| Single Population | 63.8% | 58.4% | 50.2% |
| Never Married | 46.5% | 38.6% | 33.8% |
| Divorced | 12.8% | 12.6% | 10.8% |
| Widowed | 4.6% | 7.3% | 5.6% |
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| Household Size | 2.82 | 2.44 | 2.60 |
| Households | 996 | 3,101 | 124,010,992 |
| Family Households | 707 | 2,094 | 80,755,759 |
| Married couple, w/children | 18.7% | 27.8% | 30.5% |
| Married couple, no children | 26.2% | 30.4% | 42.9% |
| Non Family Households | 289 | 1,007 | 43,255,233 |
| Single householder, w/children | 45.3% | 26.3% | 15.8% |
| Single householder, no children | 9.9% | 15.5% | 10.8% |