| | Liberty Lake, WA | Ellensburg, WA | United States |
| Population | 11,647 | 19,215 | 329,725,481 |
| Female Population | 54.3% | 49.7% | 50.5% |
| Male Population | 45.7% | 50.3% | 49.5% |
| Median Age | 36.1 | 24.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 7,618 | 18,332 | 309,327,143 |
| Population - 2000 | 4,660 | 15,414 | 285,036,114 |
| Population - 1990 | 2,015 | 12,361 | 251,960,433 |
| Pop. 2000 to Now | 145.3% | 40.0% | 15.6% |
| Pop. 1990 to Now | 467.3% | 74.6% | 30.8% |
| space4 | | | |
| Population Density | 1,896.3 | 2,503.3 | 93.4 |
| Land Area | 6.1 | 7.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Liberty Lake, WA | Ellensburg, WA | United States |
| Age 0 to 4 | 7.8% | 4.4% | 5.9% |
| Age 5 to 9 | 12.1% | 3.7% | 6.1% |
| Age 10 to 14 | 6.4% | 3.3% | 6.6% |
| Age 15 to 17 | 5.6% | 2.1% | 3.9% |
| Age 18 to 20 | 3.5% | 20.1% | 4.0% |
| Age 21 to 24 | 2.1% | 18.6% | 5.2% |
| Age 25 to 34 | 10.7% | 14.6% | 13.8% |
| Age 35 to 44 | 17.5% | 8.4% | 12.9% |
| Age 45 to 54 | 11.7% | 8.0% | 12.6% |
| Age 55 to 59 | 4.6% | 3.6% | 6.7% |
| Age 60 to 64 | 5.2% | 3.6% | 6.3% |
| Age 65 to 74 | 7.7% | 5.2% | 9.6% |
| Age 75 to 84 | 4.1% | 3.1% | 4.5% |
| Age 85 and over | 1.1% | 1.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Liberty Lake, WA | Ellensburg, WA | United States |
| White | 90.1% | 78.1% | 59.4% |
| Black | 0.0% | 1.9% | 12.2% |
| Asian | 1.8% | 2.2% | 5.6% |
| Native American | 0.9% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.8% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 4.0% | 6.7% | 3.2% |
| Hispanic | 3.0% | 10.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Liberty Lake, WA | Ellensburg, WA | United States |
| Married Population | 61.5% | 28.6% | 49.8% |
| Currently Married | 60.6% | 27.7% | 48.0% |
| Married but Separated | 0.9% | 1.0% | 1.8% |
| Single Population | 38.5% | 71.4% | 50.2% |
| Never Married | 22.5% | 58.1% | 33.8% |
| Divorced | 11.1% | 10.0% | 10.8% |
| Widowed | 4.8% | 3.3% | 5.6% |
| space5 | | | |
| Household Size | 2.72 | 2.04 | 2.60 |
| Households | 4,287 | 8,235 | 124,010,992 |
| Family Households | 2,994 | 3,364 | 80,755,759 |
| Married couple, w/children | 47.6% | 26.1% | 30.5% |
| Married couple, no children | 39.0% | 39.6% | 42.9% |
| Non Family Households | 1,293 | 4,871 | 43,255,233 |
| Single householder, w/children | 11.8% | 18.8% | 15.8% |
| Single householder, no children | 1.7% | 15.5% | 10.8% |