| | Rapid Valley, SD | Ackley, IA | United States |
| Population | 7,875 | 1,706 | 329,725,481 |
| Female Population | 45.0% | 54.6% | 50.5% |
| Male Population | 55.0% | 45.4% | 49.5% |
| Median Age | 39.2 | 41.5 | 38.4 |
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| Population - 2010 | 8,130 | 1,587 | 309,327,143 |
| Population - 2000 | 7,043 | 1,809 | 285,036,114 |
| Population - 1990 | 5,968 | 1,696 | 251,960,433 |
| Pop. 2000 to Now | 37.4% | -17.9% | 15.6% |
| Pop. 1990 to Now | 62.2% | -12.4% | 30.8% |
| space4 | | | |
| Population Density | 1,211.5 | 696.0 | 93.4 |
| Land Area | 6.5 | 2.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Rapid Valley, SD | Ackley, IA | United States |
| Age 0 to 4 | 6.0% | 5.7% | 5.9% |
| Age 5 to 9 | 5.3% | 5.5% | 6.1% |
| Age 10 to 14 | 5.8% | 7.2% | 6.6% |
| Age 15 to 17 | 6.6% | 5.2% | 3.9% |
| Age 18 to 20 | 2.6% | 2.2% | 4.0% |
| Age 21 to 24 | 7.1% | 2.8% | 5.2% |
| Age 25 to 34 | 9.9% | 11.7% | 13.8% |
| Age 35 to 44 | 14.8% | 14.1% | 12.9% |
| Age 45 to 54 | 15.0% | 13.1% | 12.6% |
| Age 55 to 59 | 4.5% | 7.6% | 6.7% |
| Age 60 to 64 | 9.6% | 4.5% | 6.3% |
| Age 65 to 74 | 8.8% | 6.9% | 9.6% |
| Age 75 to 84 | 2.8% | 8.7% | 4.5% |
| Age 85 and over | 1.1% | 4.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Rapid Valley, SD | Ackley, IA | United States |
| White | 77.6% | 81.9% | 59.4% |
| Black | 1.4% | 0.0% | 12.2% |
| Asian | 2.5% | 0.8% | 5.6% |
| Native American | 6.7% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.9% | 0.4% |
| Two or More Races | 5.4% | 2.1% | 3.2% |
| Hispanic | 6.4% | 14.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Rapid Valley, SD | Ackley, IA | United States |
| Married Population | 49.8% | 52.8% | 49.8% |
| Currently Married | 49.8% | 50.1% | 48.0% |
| Married but Separated | 0.0% | 2.7% | 1.8% |
| Single Population | 50.2% | 47.2% | 50.2% |
| Never Married | 34.3% | 30.3% | 33.8% |
| Divorced | 12.8% | 6.2% | 10.8% |
| Widowed | 3.1% | 10.7% | 5.6% |
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| Household Size | 2.51 | 2.35 | 2.60 |
| Households | 3,142 | 705 | 124,010,992 |
| Family Households | 2,164 | 409 | 80,755,759 |
| Married couple, w/children | 23.8% | 33.0% | 30.5% |
| Married couple, no children | 48.5% | 47.2% | 42.9% |
| Non Family Households | 978 | 296 | 43,255,233 |
| Single householder, w/children | 20.6% | 14.2% | 15.8% |
| Single householder, no children | 7.1% | 5.6% | 10.8% |