| | Millwood, WA | Maple Valley, WA | United States |
| Population | 1,896 | 27,643 | 329,725,481 |
| Female Population | 51.6% | 48.6% | 50.5% |
| Male Population | 48.4% | 51.4% | 49.5% |
| Median Age | 37.5 | 36.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,786 | 22,854 | 309,327,143 |
| Population - 2000 | 1,649 | 14,209 | 285,036,114 |
| Population - 1990 | 1,559 | 1,211 | 251,960,433 |
| Pop. 2000 to Now | 9.2% | 93.9% | 15.6% |
| Pop. 1990 to Now | 15.5% | 2,174.5% | 30.8% |
| space4 | | | |
| Population Density | 2,724.1 | 4,604.9 | 93.4 |
| Land Area | 0.7 | 6.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Millwood, WA | Maple Valley, WA | United States |
| Age 0 to 4 | 7.4% | 6.5% | 5.9% |
| Age 5 to 9 | 6.7% | 10.1% | 6.1% |
| Age 10 to 14 | 6.2% | 9.9% | 6.6% |
| Age 15 to 17 | 4.0% | 5.2% | 3.9% |
| Age 18 to 20 | 3.1% | 3.6% | 4.0% |
| Age 21 to 24 | 4.7% | 2.3% | 5.2% |
| Age 25 to 34 | 13.8% | 10.3% | 13.8% |
| Age 35 to 44 | 12.9% | 18.7% | 12.9% |
| Age 45 to 54 | 11.3% | 14.0% | 12.6% |
| Age 55 to 59 | 7.8% | 5.5% | 6.7% |
| Age 60 to 64 | 7.5% | 5.0% | 6.3% |
| Age 65 to 74 | 10.1% | 5.2% | 9.6% |
| Age 75 to 84 | 2.8% | 2.2% | 4.5% |
| Age 85 and over | 1.5% | 1.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Millwood, WA | Maple Valley, WA | United States |
| White | 87.4% | 75.9% | 59.4% |
| Black | 0.8% | 1.7% | 12.2% |
| Asian | 1.0% | 10.0% | 5.6% |
| Native American | 0.4% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.3% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 6.6% | 7.5% | 3.2% |
| Hispanic | 3.7% | 4.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Millwood, WA | Maple Valley, WA | United States |
| Married Population | 43.5% | 64.7% | 49.8% |
| Currently Married | 42.3% | 64.6% | 48.0% |
| Married but Separated | 1.3% | 0.1% | 1.8% |
| Single Population | 56.5% | 35.3% | 50.2% |
| Never Married | 36.3% | 22.7% | 33.8% |
| Divorced | 15.0% | 8.9% | 10.8% |
| Widowed | 5.2% | 3.7% | 5.6% |
| space5 | | | |
| Household Size | 2.46 | 3.03 | 2.60 |
| Households | 768 | 9,132 | 124,010,992 |
| Family Households | 450 | 7,514 | 80,755,759 |
| Married couple, w/children | 25.6% | 47.5% | 30.5% |
| Married couple, no children | 42.0% | 36.3% | 42.9% |
| Non Family Households | 318 | 1,618 | 43,255,233 |
| Single householder, w/children | 23.6% | 13.3% | 15.8% |
| Single householder, no children | 8.9% | 2.9% | 10.8% |