| Place Name | Onawa |
| Place Type | City |
| ZIP Code(s) | 51040 |
| County | Monona County |
| Area Code(s) | 712 |
| Timezone | Central Standard Time (CST) |
| Population (2022) | 2,985 |
| Population Growth Rate (2010-19) | -3.07% |
| Majority Ethnicity | White 95.06% |
| US Congressional District(s) | Iowa 4th |
| State House Districts | 17 |
| State Senate Districts | 9 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 95.06% |
| African American | 0.07% |
| Hispanic | 1.31% |
| Asian | 0% |
| Native American | 1.14% |
| Hawaiin/Pacific Islander | 2.42% |