| | Yountville, CA | Mill Valley, CA | United States |
| Population | 3,351 | 14,240 | 329,725,481 |
| Female Population | 51.5% | 52.5% | 50.5% |
| Male Population | 48.5% | 47.5% | 49.5% |
| Median Age | 62.3 | 47.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,941 | 13,934 | 309,327,143 |
| Population - 2000 | 2,916 | 13,600 | 285,036,114 |
| Population - 1990 | 3,259 | 13,038 | 251,960,433 |
| Pop. 2000 to Now | 1.9% | 5.3% | 15.6% |
| Pop. 1990 to Now | -8.9% | 9.9% | 30.8% |
| space4 | | | |
| Population Density | 2,253.5 | 2,989.7 | 93.4 |
| Land Area | 1.5 | 4.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Yountville, CA | Mill Valley, CA | United States |
| Age 0 to 4 | 0.3% | 2.9% | 5.9% |
| Age 5 to 9 | 2.7% | 5.8% | 6.1% |
| Age 10 to 14 | 4.1% | 6.3% | 6.6% |
| Age 15 to 17 | 1.4% | 6.1% | 3.9% |
| Age 18 to 20 | 1.5% | 3.4% | 4.0% |
| Age 21 to 24 | 0.7% | 1.5% | 5.2% |
| Age 25 to 34 | 9.1% | 7.3% | 13.8% |
| Age 35 to 44 | 7.0% | 12.2% | 12.9% |
| Age 45 to 54 | 8.6% | 18.4% | 12.6% |
| Age 55 to 59 | 12.1% | 7.8% | 6.7% |
| Age 60 to 64 | 8.8% | 7.1% | 6.3% |
| Age 65 to 74 | 21.3% | 11.6% | 9.6% |
| Age 75 to 84 | 10.9% | 6.5% | 4.5% |
| Age 85 and over | 11.3% | 3.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Yountville, CA | Mill Valley, CA | United States |
| White | 67.9% | 83.0% | 59.4% |
| Black | 3.3% | 1.4% | 12.2% |
| Asian | 3.7% | 6.1% | 5.6% |
| Native American | 0.2% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.4% | 1.0% | 0.4% |
| Two or More Races | 2.4% | 5.4% | 3.2% |
| Hispanic | 22.1% | 3.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Yountville, CA | Mill Valley, CA | United States |
| Married Population | 41.2% | 56.1% | 49.8% |
| Currently Married | 40.4% | 55.6% | 48.0% |
| Married but Separated | 0.8% | 0.5% | 1.8% |
| Single Population | 58.8% | 43.9% | 50.2% |
| Never Married | 19.9% | 26.9% | 33.8% |
| Divorced | 21.6% | 12.5% | 10.8% |
| Widowed | 17.3% | 4.5% | 5.6% |
| space5 | | | |
| Household Size | 1.78 | 2.52 | 2.60 |
| Households | 1,606 | 5,622 | 124,010,992 |
| Family Households | 731 | 3,814 | 80,755,759 |
| Married couple, w/children | 16.7% | 35.2% | 30.5% |
| Married couple, no children | 57.5% | 49.5% | 42.9% |
| Non Family Households | 875 | 1,808 | 43,255,233 |
| Single householder, w/children | 18.6% | 9.8% | 15.8% |
| Single householder, no children | 7.3% | 5.6% | 10.8% |