| | Kelso, WA | Sierra Vista Southeast, AZ | United States |
| Population | 12,566 | 14,822 | 329,725,481 |
| Female Population | 48.5% | 52.9% | 50.5% |
| Male Population | 51.5% | 47.1% | 49.5% |
| Median Age | 38.2 | 46.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 11,902 | 15,297 | 309,327,143 |
| Population - 2000 | 11,895 | 14,348 | 285,036,114 |
| Population - 1990 | 11,820 | 9,237 | 251,960,433 |
| Pop. 2000 to Now | 4.6% | 9.4% | 15.6% |
| Pop. 1990 to Now | 5.2% | 69.9% | 30.8% |
| space4 | | | |
| Population Density | 1,558.7 | 133.7 | 93.4 |
| Land Area | 8.1 | 110.9 | 3,531,905.4 |
| Water Area | 0.3 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Kelso, WA | Sierra Vista Southeast, AZ | United States |
| Age 0 to 4 | 6.4% | 4.2% | 5.9% |
| Age 5 to 9 | 6.3% | 6.2% | 6.1% |
| Age 10 to 14 | 6.9% | 8.1% | 6.6% |
| Age 15 to 17 | 3.2% | 5.6% | 3.9% |
| Age 18 to 20 | 3.0% | 3.3% | 4.0% |
| Age 21 to 24 | 4.8% | 2.5% | 5.2% |
| Age 25 to 34 | 16.6% | 7.3% | 13.8% |
| Age 35 to 44 | 11.3% | 11.2% | 12.9% |
| Age 45 to 54 | 11.7% | 11.0% | 12.6% |
| Age 55 to 59 | 6.7% | 6.6% | 6.7% |
| Age 60 to 64 | 9.3% | 10.0% | 6.3% |
| Age 65 to 74 | 7.8% | 12.9% | 9.6% |
| Age 75 to 84 | 3.8% | 8.7% | 4.5% |
| Age 85 and over | 2.4% | 2.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Kelso, WA | Sierra Vista Southeast, AZ | United States |
| White | 76.5% | 66.1% | 59.4% |
| Black | 1.9% | 0.7% | 12.2% |
| Asian | 0.6% | 1.3% | 5.6% |
| Native American | 0.3% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 0.0% | 0.2% |
| Other | 0.0% | 0.3% | 0.4% |
| Two or More Races | 4.3% | 5.3% | 3.2% |
| Hispanic | 16.3% | 26.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Kelso, WA | Sierra Vista Southeast, AZ | United States |
| Married Population | 43.3% | 60.8% | 49.8% |
| Currently Married | 39.7% | 58.7% | 48.0% |
| Married but Separated | 3.6% | 2.1% | 1.8% |
| Single Population | 56.7% | 39.2% | 50.2% |
| Never Married | 33.4% | 22.1% | 33.8% |
| Divorced | 16.9% | 10.3% | 10.8% |
| Widowed | 6.4% | 6.9% | 5.6% |
| space5 | | | |
| Household Size | 2.45 | 2.42 | 2.60 |
| Households | 5,112 | 6,118 | 124,010,992 |
| Family Households | 3,239 | 3,958 | 80,755,759 |
| Married couple, w/children | 19.2% | 33.6% | 30.5% |
| Married couple, no children | 39.8% | 52.0% | 42.9% |
| Non Family Households | 1,873 | 2,160 | 43,255,233 |
| Single householder, w/children | 27.3% | 6.3% | 15.8% |
| Single householder, no children | 13.7% | 8.1% | 10.8% |