| | Elk Plain, WA | Springfield, MO | United States |
| Population | 15,157 | 168,603 | 329,725,481 |
| Female Population | 49.4% | 51.6% | 50.5% |
| Male Population | 50.6% | 48.5% | 49.5% |
| Median Age | 35.8 | 33.2 | 38.4 |
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| Population - 2010 | 14,266 | 159,374 | 309,327,143 |
| Population - 2000 | 15,697 | 151,580 | 285,036,114 |
| Population - 1990 | 12,197 | 140,494 | 251,960,433 |
| Pop. 2000 to Now | -1.5% | 10.9% | 15.6% |
| Pop. 1990 to Now | 26.7% | 19.6% | 30.8% |
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| Population Density | 1,970.5 | 2,047.5 | 93.4 |
| Land Area | 7.7 | 82.3 | 3,531,905.4 |
| Water Area | 0.0 | 0.6 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Elk Plain, WA | Springfield, MO | United States |
| Age 0 to 4 | 5.1% | 5.3% | 5.9% |
| Age 5 to 9 | 6.8% | 5.0% | 6.1% |
| Age 10 to 14 | 6.2% | 4.5% | 6.6% |
| Age 15 to 17 | 3.5% | 2.7% | 3.9% |
| Age 18 to 20 | 3.1% | 8.1% | 4.0% |
| Age 21 to 24 | 3.8% | 11.1% | 5.2% |
| Age 25 to 34 | 19.7% | 15.3% | 13.8% |
| Age 35 to 44 | 10.9% | 11.2% | 12.9% |
| Age 45 to 54 | 13.0% | 10.2% | 12.6% |
| Age 55 to 59 | 7.6% | 5.5% | 6.7% |
| Age 60 to 64 | 8.3% | 5.2% | 6.3% |
| Age 65 to 74 | 7.9% | 8.7% | 9.6% |
| Age 75 to 84 | 3.5% | 4.8% | 4.5% |
| Age 85 and over | 0.6% | 2.4% | 1.9% |
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| Race | | | |
| | Elk Plain, WA | Springfield, MO | United States |
| White | 72.9% | 84.8% | 59.4% |
| Black | 3.1% | 3.9% | 12.2% |
| Asian | 4.1% | 2.0% | 5.6% |
| Native American | 1.0% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 1.9% | 0.0% | 0.2% |
| Other | 0.5% | 0.2% | 0.4% |
| Two or More Races | 6.7% | 4.1% | 3.2% |
| Hispanic | 9.7% | 4.5% | 18.4% |
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| Marriage & Family | | | |
| | Elk Plain, WA | Springfield, MO | United States |
| Married Population | 55.3% | 40.8% | 49.8% |
| Currently Married | 54.2% | 38.7% | 48.0% |
| Married but Separated | 1.1% | 2.1% | 1.8% |
| Single Population | 44.7% | 59.2% | 50.2% |
| Never Married | 28.9% | 39.3% | 33.8% |
| Divorced | 12.3% | 13.2% | 10.8% |
| Widowed | 3.5% | 6.6% | 5.6% |
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| Household Size | 3.00 | 2.01 | 2.60 |
| Households | 5,042 | 78,824 | 124,010,992 |
| Family Households | 3,669 | 37,582 | 80,755,759 |
| Married couple, w/children | 32.6% | 25.0% | 30.5% |
| Married couple, no children | 49.4% | 44.3% | 42.9% |
| Non Family Households | 1,373 | 41,242 | 43,255,233 |
| Single householder, w/children | 12.0% | 18.2% | 15.8% |
| Single householder, no children | 6.0% | 12.5% | 10.8% |