| | Grand Coulee, WA | Banks Lake South, WA | United States |
| Population | 1,121 | 133 | 329,725,481 |
| Female Population | 47.6% | 54.9% | 50.5% |
| Male Population | 52.4% | 45.1% | 49.5% |
| Median Age | 50.7 | 54.5 | 38.4 |
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| Population - 2010 | 1,036 | 139 | 309,327,143 |
| Population - 2000 | 897 | 160 | 285,036,114 |
| Population - 1990 | 984 | 184 | 251,960,433 |
| Pop. 2000 to Now | 17.1% | 79.4% | 15.6% |
| Pop. 1990 to Now | 6.7% | 56.0% | 30.8% |
| space4 | | | |
| Population Density | 921.1 | 54.5 | 93.4 |
| Land Area | 1.2 | 2.4 | 3,531,905.4 |
| Water Area | 0.1 | 0.5 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Grand Coulee, WA | Banks Lake South, WA | United States |
| Age 0 to 4 | 1.0% | 0.0% | 5.9% |
| Age 5 to 9 | 4.0% | 2.3% | 6.1% |
| Age 10 to 14 | 6.4% | 3.0% | 6.6% |
| Age 15 to 17 | 5.1% | 5.3% | 3.9% |
| Age 18 to 20 | 5.0% | 6.8% | 4.0% |
| Age 21 to 24 | 1.4% | 3.0% | 5.2% |
| Age 25 to 34 | 13.0% | 7.5% | 13.8% |
| Age 35 to 44 | 10.4% | 9.0% | 12.9% |
| Age 45 to 54 | 9.1% | 14.3% | 12.6% |
| Age 55 to 59 | 12.5% | 17.3% | 6.7% |
| Age 60 to 64 | 6.8% | 3.0% | 6.3% |
| Age 65 to 74 | 13.7% | 15.8% | 9.6% |
| Age 75 to 84 | 7.0% | 12.8% | 4.5% |
| Age 85 and over | 4.5% | 0.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Grand Coulee, WA | Banks Lake South, WA | United States |
| White | 71.0% | 79.7% | 59.4% |
| Black | 0.0% | 0.0% | 12.2% |
| Asian | 1.1% | 5.3% | 5.6% |
| Native American | 7.3% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 0.0% | 0.2% |
| Other | 0.8% | 0.0% | 0.4% |
| Two or More Races | 5.2% | 15.0% | 3.2% |
| Hispanic | 14.5% | 0.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Grand Coulee, WA | Banks Lake South, WA | United States |
| Married Population | 45.0% | 62.7% | 49.8% |
| Currently Married | 44.8% | 50.8% | 48.0% |
| Married but Separated | 0.2% | 11.9% | 1.8% |
| Single Population | 55.0% | 37.3% | 50.2% |
| Never Married | 27.7% | 27.8% | 33.8% |
| Divorced | 19.8% | 2.4% | 10.8% |
| Widowed | 7.5% | 7.1% | 5.6% |
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| Household Size | 1.97 | 2.15 | 2.60 |
| Households | 556 | 62 | 124,010,992 |
| Family Households | 283 | 37 | 80,755,759 |
| Married couple, w/children | 21.2% | 10.8% | 30.5% |
| Married couple, no children | 47.7% | 70.3% | 42.9% |
| Non Family Households | 273 | 25 | 43,255,233 |
| Single householder, w/children | 17.3% | 8.1% | 15.8% |
| Single householder, no children | 13.8% | 10.8% | 10.8% |