| | Milliken, CO | Wapello, IA | United States |
| Population | 8,122 | 1,914 | 329,725,481 |
| Female Population | 50.1% | 46.9% | 50.5% |
| Male Population | 49.9% | 53.1% | 49.5% |
| Median Age | 34.6 | 46.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 5,640 | 2,066 | 309,327,143 |
| Population - 2000 | 2,888 | 2,124 | 285,036,114 |
| Population - 1990 | 1,605 | 2,013 | 251,960,433 |
| Pop. 2000 to Now | 200.8% | -5.9% | 15.6% |
| Pop. 1990 to Now | 441.3% | -0.7% | 30.8% |
| space4 | | | |
| Population Density | 634.2 | 1,479.1 | 93.4 |
| Land Area | 12.8 | 1.3 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Milliken, CO | Wapello, IA | United States |
| Age 0 to 4 | 9.8% | 4.2% | 5.9% |
| Age 5 to 9 | 5.6% | 1.9% | 6.1% |
| Age 10 to 14 | 3.9% | 7.5% | 6.6% |
| Age 15 to 17 | 2.7% | 3.5% | 3.9% |
| Age 18 to 20 | 1.1% | 5.2% | 4.0% |
| Age 21 to 24 | 1.5% | 5.6% | 5.2% |
| Age 25 to 34 | 27.0% | 7.1% | 13.8% |
| Age 35 to 44 | 8.7% | 13.0% | 12.9% |
| Age 45 to 54 | 11.4% | 15.4% | 12.6% |
| Age 55 to 59 | 8.1% | 6.6% | 6.7% |
| Age 60 to 64 | 5.2% | 4.1% | 6.3% |
| Age 65 to 74 | 10.9% | 15.5% | 9.6% |
| Age 75 to 84 | 4.0% | 6.8% | 4.5% |
| Age 85 and over | 0.3% | 3.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Milliken, CO | Wapello, IA | United States |
| White | 72.6% | 76.9% | 59.4% |
| Black | 0.1% | 0.9% | 12.2% |
| Asian | 0.9% | 0.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 3.4% | 3.5% | 3.2% |
| Hispanic | 22.9% | 18.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Milliken, CO | Wapello, IA | United States |
| Married Population | 64.8% | 53.6% | 49.8% |
| Currently Married | 64.5% | 52.0% | 48.0% |
| Married but Separated | 0.3% | 1.6% | 1.8% |
| Single Population | 35.2% | 46.4% | 50.2% |
| Never Married | 19.3% | 26.6% | 33.8% |
| Divorced | 11.4% | 13.2% | 10.8% |
| Widowed | 4.4% | 6.7% | 5.6% |
| space5 | | | |
| Household Size | 2.69 | 2.37 | 2.60 |
| Households | 3,020 | 793 | 124,010,992 |
| Family Households | 2,335 | 540 | 80,755,759 |
| Married couple, w/children | 40.9% | 27.4% | 30.5% |
| Married couple, no children | 45.4% | 53.0% | 42.9% |
| Non Family Households | 685 | 253 | 43,255,233 |
| Single householder, w/children | 5.9% | 12.4% | 15.8% |
| Single householder, no children | 7.9% | 7.2% | 10.8% |