| | Millsboro, DE | Oro Valley, AZ | United States |
| Population | 6,542 | 46,515 | 329,725,481 |
| Female Population | 58.9% | 51.9% | 50.5% |
| Male Population | 41.1% | 48.1% | 49.5% |
| Median Age | 43.3 | 53.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,871 | 41,061 | 309,327,143 |
| Population - 2000 | 2,360 | 29,700 | 285,036,114 |
| Population - 1990 | 1,643 | 6,670 | 251,960,433 |
| Pop. 2000 to Now | 97.7% | 57.2% | 15.6% |
| Pop. 1990 to Now | 183.9% | 599.8% | 30.8% |
| space4 | | | |
| Population Density | 1,761.0 | 1,305.4 | 93.4 |
| Land Area | 3.7 | 35.6 | 3,531,905.4 |
| Water Area | 0.2 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Millsboro, DE | Oro Valley, AZ | United States |
| Age 0 to 4 | 5.8% | 3.3% | 5.9% |
| Age 5 to 9 | 5.6% | 5.6% | 6.1% |
| Age 10 to 14 | 7.6% | 5.6% | 6.6% |
| Age 15 to 17 | 4.4% | 3.5% | 3.9% |
| Age 18 to 20 | 2.6% | 2.1% | 4.0% |
| Age 21 to 24 | 4.5% | 3.5% | 5.2% |
| Age 25 to 34 | 7.6% | 8.0% | 13.8% |
| Age 35 to 44 | 16.2% | 9.3% | 12.9% |
| Age 45 to 54 | 7.7% | 10.2% | 12.6% |
| Age 55 to 59 | 5.9% | 6.6% | 6.7% |
| Age 60 to 64 | 4.9% | 7.8% | 6.3% |
| Age 65 to 74 | 17.1% | 19.6% | 9.6% |
| Age 75 to 84 | 9.0% | 10.7% | 4.5% |
| Age 85 and over | 1.1% | 4.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Millsboro, DE | Oro Valley, AZ | United States |
| White | 76.0% | 74.8% | 59.4% |
| Black | 17.9% | 2.3% | 12.2% |
| Asian | 0.9% | 3.5% | 5.6% |
| Native American | 0.5% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 4.1% | 3.6% | 3.2% |
| Hispanic | 0.7% | 15.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Millsboro, DE | Oro Valley, AZ | United States |
| Married Population | 55.4% | 64.8% | 49.8% |
| Currently Married | 52.9% | 63.9% | 48.0% |
| Married but Separated | 2.5% | 0.8% | 1.8% |
| Single Population | 44.6% | 35.3% | 50.2% |
| Never Married | 21.9% | 19.0% | 33.8% |
| Divorced | 10.5% | 10.1% | 10.8% |
| Widowed | 12.2% | 6.1% | 5.6% |
| space5 | | | |
| Household Size | 2.31 | 2.24 | 2.60 |
| Households | 2,758 | 20,754 | 124,010,992 |
| Family Households | 1,798 | 14,060 | 80,755,759 |
| Married couple, w/children | 28.1% | 23.1% | 30.5% |
| Married couple, no children | 42.2% | 64.5% | 42.9% |
| Non Family Households | 960 | 6,694 | 43,255,233 |
| Single householder, w/children | 21.6% | 7.0% | 15.8% |
| Single householder, no children | 8.1% | 5.4% | 10.8% |