| | Topanga, CA | Nevada City, CA | United States |
| Population | 8,255 | 3,097 | 329,725,481 |
| Female Population | 49.7% | 52.1% | 50.5% |
| Male Population | 50.3% | 47.9% | 49.5% |
| Median Age | 45.6 | 59.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 8,520 | 3,122 | 309,327,143 |
| Population - 2000 | 7,726 | 3,001 | 285,036,114 |
| Population - 1990 | 7,560 | 2,855 | 251,960,433 |
| Pop. 2000 to Now | -1.6% | 4.2% | 15.6% |
| Pop. 1990 to Now | 0.6% | 9.5% | 30.8% |
| space4 | | | |
| Population Density | 431.5 | 1,416.7 | 93.4 |
| Land Area | 19.1 | 2.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Topanga, CA | Nevada City, CA | United States |
| Age 0 to 4 | 3.5% | 2.7% | 5.9% |
| Age 5 to 9 | 5.3% | 1.9% | 6.1% |
| Age 10 to 14 | 5.9% | 2.6% | 6.6% |
| Age 15 to 17 | 4.8% | 1.4% | 3.9% |
| Age 18 to 20 | 2.7% | 4.7% | 4.0% |
| Age 21 to 24 | 2.6% | 1.8% | 5.2% |
| Age 25 to 34 | 7.9% | 7.6% | 13.8% |
| Age 35 to 44 | 15.2% | 9.8% | 12.9% |
| Age 45 to 54 | 17.8% | 11.0% | 12.6% |
| Age 55 to 59 | 6.7% | 7.2% | 6.7% |
| Age 60 to 64 | 8.0% | 8.1% | 6.3% |
| Age 65 to 74 | 9.8% | 33.3% | 9.6% |
| Age 75 to 84 | 8.3% | 5.5% | 4.5% |
| Age 85 and over | 1.5% | 2.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Topanga, CA | Nevada City, CA | United States |
| White | 67.6% | 87.6% | 59.4% |
| Black | 1.7% | 1.5% | 12.2% |
| Asian | 11.6% | 0.8% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 1.4% | 0.0% | 0.4% |
| Two or More Races | 4.4% | 5.0% | 3.2% |
| Hispanic | 13.3% | 5.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Topanga, CA | Nevada City, CA | United States |
| Married Population | 59.3% | 32.7% | 49.8% |
| Currently Married | 58.7% | 31.6% | 48.0% |
| Married but Separated | 0.5% | 1.1% | 1.8% |
| Single Population | 40.7% | 67.3% | 50.2% |
| Never Married | 28.6% | 35.2% | 33.8% |
| Divorced | 8.3% | 27.4% | 10.8% |
| Widowed | 3.8% | 4.7% | 5.6% |
| space5 | | | |
| Household Size | 2.72 | 1.98 | 2.60 |
| Households | 3,031 | 1,438 | 124,010,992 |
| Family Households | 2,162 | 581 | 80,755,759 |
| Married couple, w/children | 29.8% | 5.3% | 30.5% |
| Married couple, no children | 51.4% | 60.9% | 42.9% |
| Non Family Households | 869 | 857 | 43,255,233 |
| Single householder, w/children | 12.7% | 18.8% | 15.8% |
| Single householder, no children | 6.1% | 15.0% | 10.8% |