| | Irwin, IA | Audubon, IA | United States |
| Population | 348 | 2,065 | 329,725,481 |
| Female Population | 48.6% | 48.4% | 50.5% |
| Male Population | 51.4% | 51.6% | 49.5% |
| Median Age | 49 | 47.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 341 | 2,157 | 309,327,143 |
| Population - 2000 | 372 | 2,382 | 285,036,114 |
| Population - 1990 | 394 | 2,524 | 251,960,433 |
| Pop. 2000 to Now | -17.2% | -21.2% | 15.6% |
| Pop. 1990 to Now | -21.8% | -25.6% | 30.8% |
| space4 | | | |
| Population Density | 583.9 | 1,080.6 | 93.4 |
| Land Area | 0.6 | 1.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Irwin, IA | Audubon, IA | United States |
| Age 0 to 4 | 3.2% | 5.8% | 5.9% |
| Age 5 to 9 | 5.2% | 3.2% | 6.1% |
| Age 10 to 14 | 7.5% | 6.7% | 6.6% |
| Age 15 to 17 | 2.6% | 6.0% | 3.9% |
| Age 18 to 20 | 0.9% | 4.2% | 4.0% |
| Age 21 to 24 | 6.6% | 5.1% | 5.2% |
| Age 25 to 34 | 10.9% | 11.0% | 13.8% |
| Age 35 to 44 | 5.2% | 6.4% | 12.9% |
| Age 45 to 54 | 15.5% | 9.2% | 12.6% |
| Age 55 to 59 | 7.8% | 8.9% | 6.7% |
| Age 60 to 64 | 8.9% | 5.9% | 6.3% |
| Age 65 to 74 | 13.8% | 11.5% | 9.6% |
| Age 75 to 84 | 9.5% | 9.9% | 4.5% |
| Age 85 and over | 2.6% | 6.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Irwin, IA | Audubon, IA | United States |
| White | 99.1% | 94.2% | 59.4% |
| Black | 0.0% | 0.7% | 12.2% |
| Asian | 0.0% | 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 | 0.0% | 4.0% | 3.2% |
| Hispanic | 0.9% | 1.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Irwin, IA | Audubon, IA | United States |
| Married Population | 58.7% | 46.2% | 49.8% |
| Currently Married | 58.7% | 44.7% | 48.0% |
| Married but Separated | 0.0% | 1.5% | 1.8% |
| Single Population | 41.3% | 53.8% | 50.2% |
| Never Married | 21.5% | 29.7% | 33.8% |
| Divorced | 14.0% | 10.9% | 10.8% |
| Widowed | 5.8% | 13.2% | 5.6% |
| space5 | | | |
| Household Size | 2.35 | 2.06 | 2.60 |
| Households | 148 | 978 | 124,010,992 |
| Family Households | 104 | 525 | 80,755,759 |
| Married couple, w/children | 25.0% | 21.7% | 30.5% |
| Married couple, no children | 56.7% | 52.2% | 42.9% |
| Non Family Households | 44 | 453 | 43,255,233 |
| Single householder, w/children | 7.7% | 20.2% | 15.8% |
| Single householder, no children | 10.6% | 5.9% | 10.8% |