| | California, MD | Johnstown, PA | United States |
| Population | 14,129 | 18,647 | 329,725,481 |
| Female Population | 50.0% | 53.0% | 50.5% |
| Male Population | 50.0% | 47.0% | 49.5% |
| Median Age | 35.6 | 44.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 11,970 | 20,944 | 309,327,143 |
| Population - 2000 | 9,307 | 23,906 | 285,036,114 |
| Population - 1990 | 7,626 | 28,134 | 251,960,433 |
| Pop. 2000 to Now | 49.1% | -20.8% | 15.6% |
| Pop. 1990 to Now | 81.9% | -32.7% | 30.8% |
| space4 | | | |
| Population Density | 1,097.7 | 3,164.3 | 93.4 |
| Land Area | 12.9 | 5.9 | 3,531,905.4 |
| Water Area | 2.1 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | California, MD | Johnstown, PA | United States |
| Age 0 to 4 | 5.1% | 6.2% | 5.9% |
| Age 5 to 9 | 6.0% | 7.3% | 6.1% |
| Age 10 to 14 | 9.1% | 6.4% | 6.6% |
| Age 15 to 17 | 5.3% | 3.4% | 3.9% |
| Age 18 to 20 | 4.2% | 2.9% | 4.0% |
| Age 21 to 24 | 3.9% | 3.1% | 5.2% |
| Age 25 to 34 | 15.3% | 11.3% | 13.8% |
| Age 35 to 44 | 13.7% | 9.9% | 12.9% |
| Age 45 to 54 | 15.7% | 13.4% | 12.6% |
| Age 55 to 59 | 6.7% | 7.0% | 6.7% |
| Age 60 to 64 | 5.1% | 9.0% | 6.3% |
| Age 65 to 74 | 6.4% | 11.7% | 9.6% |
| Age 75 to 84 | 2.8% | 5.4% | 4.5% |
| Age 85 and over | 0.7% | 2.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | California, MD | Johnstown, PA | United States |
| White | 63.3% | 72.1% | 59.4% |
| Black | 24.1% | 16.2% | 12.2% |
| Asian | 3.6% | 0.4% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.6% | 1.1% | 0.4% |
| Two or More Races | 3.2% | 5.6% | 3.2% |
| Hispanic | 4.9% | 4.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | California, MD | Johnstown, PA | United States |
| Married Population | 53.5% | 35.5% | 49.8% |
| Currently Married | 51.5% | 31.5% | 48.0% |
| Married but Separated | 2.1% | 4.0% | 1.8% |
| Single Population | 46.5% | 64.5% | 50.2% |
| Never Married | 32.7% | 40.8% | 33.8% |
| Divorced | 8.9% | 15.3% | 10.8% |
| Widowed | 4.8% | 8.4% | 5.6% |
| space5 | | | |
| Household Size | 2.64 | 2.06 | 2.60 |
| Households | 5,343 | 8,991 | 124,010,992 |
| Family Households | 3,609 | 4,208 | 80,755,759 |
| Married couple, w/children | 36.4% | 12.6% | 30.5% |
| Married couple, no children | 39.7% | 36.8% | 42.9% |
| Non Family Households | 1,734 | 4,783 | 43,255,233 |
| Single householder, w/children | 16.9% | 32.5% | 15.8% |
| Single householder, no children | 6.9% | 18.0% | 10.8% |