| | Union Gap, WA | Pendleton, OR | United States |
| Population | 6,499 | 16,861 | 329,725,481 |
| Female Population | 49.9% | 45.6% | 50.5% |
| Male Population | 50.1% | 54.4% | 49.5% |
| Median Age | 33.4 | 36.9 | 38.4 |
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| Population - 2010 | 6,132 | 16,656 | 309,327,143 |
| Population - 2000 | 5,621 | 16,354 | 285,036,114 |
| Population - 1990 | 3,120 | 15,126 | 251,960,433 |
| Pop. 2000 to Now | 9.6% | 1.5% | 15.6% |
| Pop. 1990 to Now | 97.4% | 9.7% | 30.8% |
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| Population Density | 1,164.3 | 1,438.3 | 93.4 |
| Land Area | 5.6 | 11.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Union Gap, WA | Pendleton, OR | United States |
| Age 0 to 4 | 8.5% | 7.5% | 5.9% |
| Age 5 to 9 | 8.6% | 6.1% | 6.1% |
| Age 10 to 14 | 4.9% | 7.0% | 6.6% |
| Age 15 to 17 | 5.3% | 4.1% | 3.9% |
| Age 18 to 20 | 6.2% | 4.5% | 4.0% |
| Age 21 to 24 | 4.2% | 3.7% | 5.2% |
| Age 25 to 34 | 13.8% | 14.1% | 13.8% |
| Age 35 to 44 | 15.0% | 14.0% | 12.9% |
| Age 45 to 54 | 11.2% | 11.0% | 12.6% |
| Age 55 to 59 | 9.1% | 5.8% | 6.7% |
| Age 60 to 64 | 2.9% | 5.5% | 6.3% |
| Age 65 to 74 | 5.5% | 10.4% | 9.6% |
| Age 75 to 84 | 3.4% | 3.6% | 4.5% |
| Age 85 and over | 1.4% | 2.6% | 1.9% |
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| Race | | | |
| | Union Gap, WA | Pendleton, OR | United States |
| White | 38.2% | 78.4% | 59.4% |
| Black | 0.0% | 1.9% | 12.2% |
| Asian | 3.2% | 0.6% | 5.6% |
| Native American | 6.3% | 2.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.7% | 0.4% |
| Two or More Races | 0.9% | 4.2% | 3.2% |
| Hispanic | 51.4% | 12.0% | 18.4% |
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| Marriage & Family | | | |
| | Union Gap, WA | Pendleton, OR | United States |
| Married Population | 46.5% | 44.8% | 49.8% |
| Currently Married | 41.9% | 42.3% | 48.0% |
| Married but Separated | 4.6% | 2.6% | 1.8% |
| Single Population | 53.5% | 55.2% | 50.2% |
| Never Married | 41.4% | 33.7% | 33.8% |
| Divorced | 7.6% | 14.8% | 10.8% |
| Widowed | 4.5% | 6.7% | 5.6% |
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| Household Size | 3.10 | 2.57 | 2.60 |
| Households | 2,073 | 5,876 | 124,010,992 |
| Family Households | 1,464 | 3,555 | 80,755,759 |
| Married couple, w/children | 26.7% | 32.9% | 30.5% |
| Married couple, no children | 38.8% | 37.1% | 42.9% |
| Non Family Households | 609 | 2,321 | 43,255,233 |
| Single householder, w/children | 25.7% | 22.4% | 15.8% |
| Single householder, no children | 8.8% | 7.6% | 10.8% |