| | Fountain, CO | Sebastopol, CA | United States |
| Population | 29,495 | 7,563 | 329,725,481 |
| Female Population | 50.1% | 53.8% | 50.5% |
| Male Population | 49.9% | 46.3% | 49.5% |
| Median Age | 30.3 | 49.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 26,106 | 7,474 | 309,327,143 |
| Population - 2000 | 15,197 | 7,774 | 285,036,114 |
| Population - 1990 | 9,984 | 7,004 | 251,960,433 |
| Pop. 2000 to Now | 104.1% | -2.3% | 15.6% |
| Pop. 1990 to Now | 210.7% | 8.4% | 30.8% |
| space4 | | | |
| Population Density | 1,313.6 | 4,066.1 | 93.4 |
| Land Area | 22.5 | 1.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Fountain, CO | Sebastopol, CA | United States |
| Age 0 to 4 | 7.4% | 3.4% | 5.9% |
| Age 5 to 9 | 6.0% | 4.0% | 6.1% |
| Age 10 to 14 | 9.1% | 5.5% | 6.6% |
| Age 15 to 17 | 5.8% | 2.3% | 3.9% |
| Age 18 to 20 | 3.0% | 2.9% | 4.0% |
| Age 21 to 24 | 7.2% | 5.4% | 5.2% |
| Age 25 to 34 | 17.8% | 12.3% | 13.8% |
| Age 35 to 44 | 16.6% | 9.6% | 12.9% |
| Age 45 to 54 | 12.7% | 13.3% | 12.6% |
| Age 55 to 59 | 5.6% | 7.1% | 6.7% |
| Age 60 to 64 | 3.0% | 9.4% | 6.3% |
| Age 65 to 74 | 3.7% | 17.8% | 9.6% |
| Age 75 to 84 | 1.4% | 4.5% | 4.5% |
| Age 85 and over | 0.7% | 2.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Fountain, CO | Sebastopol, CA | United States |
| White | 54.4% | 72.0% | 59.4% |
| Black | 10.4% | 2.3% | 12.2% |
| Asian | 2.7% | 4.4% | 5.6% |
| Native American | 0.4% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 0.2% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 4.5% | 6.4% | 3.2% |
| Hispanic | 27.3% | 14.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Fountain, CO | Sebastopol, CA | United States |
| Married Population | 58.6% | 49.7% | 49.8% |
| Currently Married | 57.5% | 48.7% | 48.0% |
| Married but Separated | 1.1% | 1.0% | 1.8% |
| Single Population | 41.4% | 50.3% | 50.2% |
| Never Married | 28.6% | 29.1% | 33.8% |
| Divorced | 10.4% | 17.0% | 10.8% |
| Widowed | 2.4% | 4.3% | 5.6% |
| space5 | | | |
| Household Size | 2.94 | 2.32 | 2.60 |
| Households | 10,044 | 3,221 | 124,010,992 |
| Family Households | 7,204 | 1,927 | 80,755,759 |
| Married couple, w/children | 45.7% | 30.6% | 30.5% |
| Married couple, no children | 35.6% | 46.1% | 42.9% |
| Non Family Households | 2,840 | 1,294 | 43,255,233 |
| Single householder, w/children | 12.9% | 8.1% | 15.8% |
| Single householder, no children | 5.8% | 15.2% | 10.8% |