| | Jefferson, OR | Yreka, CA | United States |
| Population | 3,329 | 7,807 | 329,725,481 |
| Female Population | 51.7% | 51.2% | 50.5% |
| Male Population | 48.3% | 48.8% | 49.5% |
| Median Age | 33.6 | 35.6 | 38.4 |
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| Population - 2010 | 3,107 | 7,791 | 309,327,143 |
| Population - 2000 | 2,487 | 7,290 | 285,036,114 |
| Population - 1990 | 1,805 | 6,948 | 251,960,433 |
| Pop. 2000 to Now | 36.2% | 2.9% | 15.6% |
| Pop. 1990 to Now | 87.6% | 8.0% | 30.8% |
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| Population Density | 3,898.1 | 781.9 | 93.4 |
| Land Area | 0.9 | 10.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Jefferson, OR | Yreka, CA | United States |
| Age 0 to 4 | 4.2% | 5.1% | 5.9% |
| Age 5 to 9 | 9.8% | 8.4% | 6.1% |
| Age 10 to 14 | 9.5% | 9.4% | 6.6% |
| Age 15 to 17 | 5.3% | 4.0% | 3.9% |
| Age 18 to 20 | 4.5% | 4.3% | 4.0% |
| Age 21 to 24 | 6.7% | 3.1% | 5.2% |
| Age 25 to 34 | 11.8% | 14.8% | 13.8% |
| Age 35 to 44 | 16.3% | 11.5% | 12.9% |
| Age 45 to 54 | 9.5% | 7.1% | 12.6% |
| Age 55 to 59 | 4.5% | 4.2% | 6.7% |
| Age 60 to 64 | 5.5% | 5.5% | 6.3% |
| Age 65 to 74 | 8.4% | 15.2% | 9.6% |
| Age 75 to 84 | 2.9% | 5.0% | 4.5% |
| Age 85 and over | 1.1% | 2.4% | 1.9% |
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| Race | | | |
| | Jefferson, OR | Yreka, CA | United States |
| White | 70.7% | 68.4% | 59.4% |
| Black | 1.2% | 2.7% | 12.2% |
| Asian | 0.0% | 0.1% | 5.6% |
| Native American | 1.1% | 2.9% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 1.8% | 0.2% |
| Other | 0.1% | 0.1% | 0.4% |
| Two or More Races | 5.0% | 6.4% | 3.2% |
| Hispanic | 21.9% | 17.6% | 18.4% |
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| Marriage & Family | | | |
| | Jefferson, OR | Yreka, CA | United States |
| Married Population | 51.9% | 41.7% | 49.8% |
| Currently Married | 49.8% | 40.0% | 48.0% |
| Married but Separated | 2.0% | 1.7% | 1.8% |
| Single Population | 48.1% | 58.3% | 50.2% |
| Never Married | 35.1% | 31.8% | 33.8% |
| Divorced | 10.2% | 16.2% | 10.8% |
| Widowed | 2.8% | 10.4% | 5.6% |
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| Household Size | 3.35 | 2.41 | 2.60 |
| Households | 991 | 3,210 | 124,010,992 |
| Family Households | 838 | 1,703 | 80,755,759 |
| Married couple, w/children | 26.7% | 27.7% | 30.5% |
| Married couple, no children | 43.7% | 37.9% | 42.9% |
| Non Family Households | 153 | 1,507 | 43,255,233 |
| Single householder, w/children | 17.4% | 28.2% | 15.8% |
| Single householder, no children | 12.2% | 6.2% | 10.8% |