| | Mill Creek, OK | Marietta, OK | United States |
| Population | 268 | 2,813 | 329,725,481 |
| Female Population | 57.8% | 51.1% | 50.5% |
| Male Population | 42.2% | 49.0% | 49.5% |
| Median Age | 50.2 | 30 | 38.4 |
| space3 | | | |
| Population - 2010 | 320 | 2,622 | 309,327,143 |
| Population - 2000 | 340 | 2,445 | 285,036,114 |
| Population - 1990 | 336 | 2,306 | 251,960,433 |
| Pop. 2000 to Now | -8.5% | 12.5% | 15.6% |
| Pop. 1990 to Now | -7.4% | 19.3% | 30.8% |
| space4 | | | |
| Population Density | 716.6 | 1,157.6 | 93.4 |
| Land Area | 0.4 | 2.4 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Mill Creek, OK | Marietta, OK | United States |
| Age 0 to 4 | 4.9% | 9.9% | 5.9% |
| Age 5 to 9 | 8.2% | 8.6% | 6.1% |
| Age 10 to 14 | 5.6% | 8.6% | 6.6% |
| Age 15 to 17 | 1.5% | 6.3% | 3.9% |
| Age 18 to 20 | 4.1% | 3.4% | 4.0% |
| Age 21 to 24 | 1.9% | 4.8% | 5.2% |
| Age 25 to 34 | 11.2% | 14.8% | 13.8% |
| Age 35 to 44 | 4.9% | 12.1% | 12.9% |
| Age 45 to 54 | 14.6% | 8.9% | 12.6% |
| Age 55 to 59 | 11.6% | 4.4% | 6.7% |
| Age 60 to 64 | 6.0% | 4.9% | 6.3% |
| Age 65 to 74 | 7.8% | 8.8% | 9.6% |
| Age 75 to 84 | 17.5% | 3.1% | 4.5% |
| Age 85 and over | 0.4% | 1.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Mill Creek, OK | Marietta, OK | United States |
| White | 70.9% | 50.3% | 59.4% |
| Black | 0.0% | 5.4% | 12.2% |
| Asian | 0.0% | 0.5% | 5.6% |
| Native American | 10.8% | 2.9% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 14.9% | 5.0% | 3.2% |
| Hispanic | 3.4% | 35.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Mill Creek, OK | Marietta, OK | United States |
| Married Population | 50.0% | 45.2% | 49.8% |
| Currently Married | 50.0% | 43.1% | 48.0% |
| Married but Separated | 0.0% | 2.1% | 1.8% |
| Single Population | 50.0% | 54.8% | 50.2% |
| Never Married | 22.5% | 33.4% | 33.8% |
| Divorced | 19.3% | 14.4% | 10.8% |
| Widowed | 8.3% | 7.0% | 5.6% |
| space5 | | | |
| Household Size | 3.31 | 3.06 | 2.60 |
| Households | 81 | 893 | 124,010,992 |
| Family Households | 49 | 597 | 80,755,759 |
| Married couple, w/children | 20.4% | 32.3% | 30.5% |
| Married couple, no children | 38.8% | 32.2% | 42.9% |
| Non Family Households | 32 | 296 | 43,255,233 |
| Single householder, w/children | 22.4% | 27.8% | 15.8% |
| Single householder, no children | 18.4% | 7.7% | 10.8% |