| | Auburn, CA | Johnstown, PA | United States |
| Population | 13,738 | 18,647 | 329,725,481 |
| Female Population | 53.4% | 53.0% | 50.5% |
| Male Population | 46.6% | 47.0% | 49.5% |
| Median Age | 48.2 | 44.4 | 38.4 |
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| Population - 2010 | 13,349 | 20,944 | 309,327,143 |
| Population - 2000 | 12,462 | 23,906 | 285,036,114 |
| Population - 1990 | 10,592 | 28,134 | 251,960,433 |
| Pop. 2000 to Now | 14.0% | -20.8% | 15.6% |
| Pop. 1990 to Now | 34.1% | -32.7% | 30.8% |
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| Population Density | 1,914.2 | 3,164.3 | 93.4 |
| Land Area | 7.2 | 5.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Auburn, CA | Johnstown, PA | United States |
| Age 0 to 4 | 3.3% | 6.2% | 5.9% |
| Age 5 to 9 | 6.6% | 7.3% | 6.1% |
| Age 10 to 14 | 4.0% | 6.4% | 6.6% |
| Age 15 to 17 | 3.4% | 3.4% | 3.9% |
| Age 18 to 20 | 3.1% | 2.9% | 4.0% |
| Age 21 to 24 | 4.0% | 3.1% | 5.2% |
| Age 25 to 34 | 8.6% | 11.3% | 13.8% |
| Age 35 to 44 | 12.5% | 9.9% | 12.9% |
| Age 45 to 54 | 12.7% | 13.4% | 12.6% |
| Age 55 to 59 | 8.3% | 7.0% | 6.7% |
| Age 60 to 64 | 9.4% | 9.0% | 6.3% |
| Age 65 to 74 | 14.3% | 11.7% | 9.6% |
| Age 75 to 84 | 8.0% | 5.4% | 4.5% |
| Age 85 and over | 1.8% | 2.9% | 1.9% |
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| Race | | | |
| | Auburn, CA | Johnstown, PA | United States |
| White | 80.6% | 72.1% | 59.4% |
| Black | 0.5% | 16.2% | 12.2% |
| Asian | 1.6% | 0.4% | 5.6% |
| Native American | 0.2% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.5% | 0.0% | 0.2% |
| Other | 0.3% | 1.1% | 0.4% |
| Two or More Races | 3.6% | 5.6% | 3.2% |
| Hispanic | 12.6% | 4.6% | 18.4% |
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| Marriage & Family | | | |
| | Auburn, CA | Johnstown, PA | United States |
| Married Population | 52.6% | 35.5% | 49.8% |
| Currently Married | 50.3% | 31.5% | 48.0% |
| Married but Separated | 2.4% | 4.0% | 1.8% |
| Single Population | 47.4% | 64.5% | 50.2% |
| Never Married | 25.6% | 40.8% | 33.8% |
| Divorced | 16.2% | 15.3% | 10.8% |
| Widowed | 5.5% | 8.4% | 5.6% |
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| Household Size | 2.15 | 2.06 | 2.60 |
| Households | 6,236 | 8,991 | 124,010,992 |
| Family Households | 3,621 | 4,208 | 80,755,759 |
| Married couple, w/children | 21.6% | 12.6% | 30.5% |
| Married couple, no children | 54.7% | 36.8% | 42.9% |
| Non Family Households | 2,615 | 4,783 | 43,255,233 |
| Single householder, w/children | 12.1% | 32.5% | 15.8% |
| Single householder, no children | 11.6% | 18.0% | 10.8% |