| | Oakley, CA | Fairfax town (Marin County), CA | United States |
| Population | 42,996 | 7,605 | 329,725,481 |
| Female Population | 49.1% | 53.5% | 50.5% |
| Male Population | 50.9% | 46.6% | 49.5% |
| Median Age | 35.5 | 48.5 | 38.4 |
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| Population - 2010 | 35,638 | 7,452 | 309,327,143 |
| Population - 2000 | 25,619 | 7,319 | 285,036,114 |
| Population - 1990 | 18,374 | 6,931 | 251,960,433 |
| Pop. 2000 to Now | 66.7% | 3.3% | 15.6% |
| Pop. 1990 to Now | 132.5% | 9.1% | 30.8% |
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| Population Density | 2,710.5 | 3,450.5 | 93.4 |
| Land Area | 15.9 | 2.2 | 3,531,905.4 |
| Water Area | 0.3 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Oakley, CA | Fairfax town (Marin County), CA | United States |
| Age 0 to 4 | 7.7% | 4.7% | 5.9% |
| Age 5 to 9 | 8.2% | 2.9% | 6.1% |
| Age 10 to 14 | 7.8% | 3.9% | 6.6% |
| Age 15 to 17 | 4.3% | 3.4% | 3.9% |
| Age 18 to 20 | 3.9% | 3.4% | 4.0% |
| Age 21 to 24 | 5.3% | 4.1% | 5.2% |
| Age 25 to 34 | 11.9% | 8.8% | 13.8% |
| Age 35 to 44 | 15.2% | 12.3% | 12.9% |
| Age 45 to 54 | 12.8% | 17.0% | 12.6% |
| Age 55 to 59 | 6.9% | 8.0% | 6.7% |
| Age 60 to 64 | 6.6% | 7.8% | 6.3% |
| Age 65 to 74 | 6.9% | 15.0% | 9.6% |
| Age 75 to 84 | 2.0% | 6.6% | 4.5% |
| Age 85 and over | 0.6% | 2.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Oakley, CA | Fairfax town (Marin County), CA | United States |
| White | 45.0% | 82.9% | 59.4% |
| Black | 8.4% | 0.9% | 12.2% |
| Asian | 7.3% | 3.8% | 5.6% |
| Native American | 0.5% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.9% | 0.7% | 0.2% |
| Other | 0.2% | 0.7% | 0.4% |
| Two or More Races | 5.5% | 2.3% | 3.2% |
| Hispanic | 32.2% | 8.7% | 18.4% |
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| Marriage & Family | | | |
| | Oakley, CA | Fairfax town (Marin County), CA | United States |
| Married Population | 56.2% | 45.9% | 49.8% |
| Currently Married | 54.9% | 45.7% | 48.0% |
| Married but Separated | 1.3% | 0.2% | 1.8% |
| Single Population | 43.8% | 54.1% | 50.2% |
| Never Married | 32.0% | 34.3% | 33.8% |
| Divorced | 7.9% | 14.4% | 10.8% |
| Widowed | 3.9% | 5.4% | 5.6% |
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| Household Size | 3.44 | 2.22 | 2.60 |
| Households | 12,480 | 3,410 | 124,010,992 |
| Family Households | 10,529 | 1,931 | 80,755,759 |
| Married couple, w/children | 40.9% | 25.2% | 30.5% |
| Married couple, no children | 37.9% | 51.3% | 42.9% |
| Non Family Households | 1,951 | 1,479 | 43,255,233 |
| Single householder, w/children | 14.2% | 13.6% | 15.8% |
| Single householder, no children | 7.0% | 9.9% | 10.8% |