| | Greenfield, IA | Corning, IA | United States |
| Population | 1,671 | 1,607 | 329,725,481 |
| Female Population | 46.6% | 53.3% | 50.5% |
| Male Population | 53.4% | 46.7% | 49.5% |
| Median Age | 53.5 | 45.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,986 | 1,632 | 309,327,143 |
| Population - 2000 | 2,129 | 1,783 | 285,036,114 |
| Population - 1990 | 2,074 | 1,806 | 251,960,433 |
| Pop. 2000 to Now | -14.9% | -20.1% | 15.6% |
| Pop. 1990 to Now | -12.6% | -21.2% | 30.8% |
| space4 | | | |
| Population Density | 921.2 | 1,012.0 | 93.4 |
| Land Area | 1.8 | 1.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Greenfield, IA | Corning, IA | United States |
| Age 0 to 4 | 3.8% | 3.7% | 5.9% |
| Age 5 to 9 | 5.4% | 8.9% | 6.1% |
| Age 10 to 14 | 4.0% | 6.8% | 6.6% |
| Age 15 to 17 | 2.9% | 3.7% | 3.9% |
| Age 18 to 20 | 1.7% | 3.9% | 4.0% |
| Age 21 to 24 | 5.6% | 1.3% | 5.2% |
| Age 25 to 34 | 11.6% | 7.7% | 13.8% |
| Age 35 to 44 | 6.7% | 13.9% | 12.9% |
| Age 45 to 54 | 9.9% | 12.9% | 12.6% |
| Age 55 to 59 | 6.8% | 4.4% | 6.7% |
| Age 60 to 64 | 10.4% | 7.0% | 6.3% |
| Age 65 to 74 | 13.2% | 14.9% | 9.6% |
| Age 75 to 84 | 10.8% | 7.7% | 4.5% |
| Age 85 and over | 7.2% | 3.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Greenfield, IA | Corning, IA | United States |
| White | 97.4% | 94.3% | 59.4% |
| Black | 1.5% | 0.2% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 0.0% | 1.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 1.1% | 2.9% | 3.2% |
| Hispanic | 0.0% | 1.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Greenfield, IA | Corning, IA | United States |
| Married Population | 43.9% | 48.1% | 49.8% |
| Currently Married | 43.4% | 47.1% | 48.0% |
| Married but Separated | 0.5% | 0.9% | 1.8% |
| Single Population | 56.1% | 51.9% | 50.2% |
| Never Married | 26.5% | 22.4% | 33.8% |
| Divorced | 15.2% | 20.3% | 10.8% |
| Widowed | 14.4% | 9.2% | 5.6% |
| space5 | | | |
| Household Size | 1.81 | 2.28 | 2.60 |
| Households | 901 | 675 | 124,010,992 |
| Family Households | 356 | 365 | 80,755,759 |
| Married couple, w/children | 24.4% | 32.3% | 30.5% |
| Married couple, no children | 53.7% | 47.9% | 42.9% |
| Non Family Households | 545 | 310 | 43,255,233 |
| Single householder, w/children | 15.7% | 11.8% | 15.8% |
| Single householder, no children | 6.2% | 7.9% | 10.8% |