| | Smyrna, DE | Clayton, DE | United States |
| Population | 12,619 | 3,845 | 329,725,481 |
| Female Population | 50.3% | 50.4% | 50.5% |
| Male Population | 49.7% | 49.6% | 49.5% |
| Median Age | 35.1 | 35.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 10,171 | 2,946 | 309,327,143 |
| Population - 2000 | 5,679 | 1,273 | 285,036,114 |
| Population - 1990 | 5,231 | 1,163 | 251,960,433 |
| Pop. 2000 to Now | 114.2% | 185.2% | 15.6% |
| Pop. 1990 to Now | 132.5% | 212.1% | 30.8% |
| space4 | | | |
| Population Density | 2,107.4 | 2,014.1 | 93.4 |
| Land Area | 6.0 | 1.9 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Smyrna, DE | Clayton, DE | United States |
| Age 0 to 4 | 5.7% | 7.5% | 5.9% |
| Age 5 to 9 | 6.5% | 12.0% | 6.1% |
| Age 10 to 14 | 6.6% | 9.0% | 6.6% |
| Age 15 to 17 | 4.4% | 5.6% | 3.9% |
| Age 18 to 20 | 2.4% | 3.6% | 4.0% |
| Age 21 to 24 | 3.9% | 2.7% | 5.2% |
| Age 25 to 34 | 20.4% | 7.5% | 13.8% |
| Age 35 to 44 | 17.1% | 16.7% | 12.9% |
| Age 45 to 54 | 12.8% | 15.5% | 12.6% |
| Age 55 to 59 | 3.2% | 4.1% | 6.7% |
| Age 60 to 64 | 4.1% | 6.7% | 6.3% |
| Age 65 to 74 | 9.1% | 5.9% | 9.6% |
| Age 75 to 84 | 2.8% | 1.9% | 4.5% |
| Age 85 and over | 1.0% | 1.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Smyrna, DE | Clayton, DE | United States |
| White | 49.2% | 49.8% | 59.4% |
| Black | 34.7% | 33.8% | 12.2% |
| Asian | 0.9% | 2.8% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 4.8% | 3.6% | 3.2% |
| Hispanic | 10.4% | 9.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Smyrna, DE | Clayton, DE | United States |
| Married Population | 47.2% | 51.8% | 49.8% |
| Currently Married | 46.7% | 49.9% | 48.0% |
| Married but Separated | 0.5% | 1.9% | 1.8% |
| Single Population | 52.8% | 48.2% | 50.2% |
| Never Married | 37.4% | 30.8% | 33.8% |
| Divorced | 10.7% | 10.8% | 10.8% |
| Widowed | 4.7% | 6.6% | 5.6% |
| space5 | | | |
| Household Size | 2.69 | 3.41 | 2.60 |
| Households | 4,621 | 1,128 | 124,010,992 |
| Family Households | 3,216 | 922 | 80,755,759 |
| Married couple, w/children | 34.6% | 45.9% | 30.5% |
| Married couple, no children | 35.2% | 23.0% | 42.9% |
| Non Family Households | 1,405 | 206 | 43,255,233 |
| Single householder, w/children | 17.4% | 22.2% | 15.8% |
| Single householder, no children | 12.8% | 8.9% | 10.8% |