| | Atlantic, IA | Audubon, IA | United States |
| Population | 6,795 | 2,065 | 329,725,481 |
| Female Population | 51.6% | 48.4% | 50.5% |
| Male Population | 48.4% | 51.6% | 49.5% |
| Median Age | 43.9 | 47.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 7,102 | 2,157 | 309,327,143 |
| Population - 2000 | 7,257 | 2,382 | 285,036,114 |
| Population - 1990 | 7,432 | 2,524 | 251,960,433 |
| Pop. 2000 to Now | -10.3% | -21.2% | 15.6% |
| Pop. 1990 to Now | -12.4% | -25.6% | 30.8% |
| space4 | | | |
| Population Density | 816.6 | 1,080.6 | 93.4 |
| Land Area | 8.3 | 1.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Atlantic, IA | Audubon, IA | United States |
| Age 0 to 4 | 6.0% | 5.8% | 5.9% |
| Age 5 to 9 | 5.7% | 3.2% | 6.1% |
| Age 10 to 14 | 4.3% | 6.7% | 6.6% |
| Age 15 to 17 | 4.2% | 6.0% | 3.9% |
| Age 18 to 20 | 1.8% | 4.2% | 4.0% |
| Age 21 to 24 | 4.6% | 5.1% | 5.2% |
| Age 25 to 34 | 11.1% | 11.0% | 13.8% |
| Age 35 to 44 | 14.3% | 6.4% | 12.9% |
| Age 45 to 54 | 11.7% | 9.2% | 12.6% |
| Age 55 to 59 | 6.9% | 8.9% | 6.7% |
| Age 60 to 64 | 6.6% | 5.9% | 6.3% |
| Age 65 to 74 | 12.6% | 11.5% | 9.6% |
| Age 75 to 84 | 5.9% | 9.9% | 4.5% |
| Age 85 and over | 4.3% | 6.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Atlantic, IA | Audubon, IA | United States |
| White | 93.2% | 94.2% | 59.4% |
| Black | 1.4% | 0.7% | 12.2% |
| Asian | 0.6% | 0.0% | 5.6% |
| Native American | 0.2% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.6% | 4.0% | 3.2% |
| Hispanic | 4.0% | 1.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Atlantic, IA | Audubon, IA | United States |
| Married Population | 50.1% | 46.2% | 49.8% |
| Currently Married | 48.9% | 44.7% | 48.0% |
| Married but Separated | 1.2% | 1.5% | 1.8% |
| Single Population | 49.9% | 53.8% | 50.2% |
| Never Married | 24.5% | 29.7% | 33.8% |
| Divorced | 17.3% | 10.9% | 10.8% |
| Widowed | 8.1% | 13.2% | 5.6% |
| space5 | | | |
| Household Size | 2.07 | 2.06 | 2.60 |
| Households | 3,202 | 978 | 124,010,992 |
| Family Households | 1,705 | 525 | 80,755,759 |
| Married couple, w/children | 28.9% | 21.7% | 30.5% |
| Married couple, no children | 45.9% | 52.2% | 42.9% |
| Non Family Households | 1,497 | 453 | 43,255,233 |
| Single householder, w/children | 16.8% | 20.2% | 15.8% |
| Single householder, no children | 8.3% | 5.9% | 10.8% |