| Place Name | Union |
| Place Type | City |
| ZIP Code(s) | 50258 |
| County | Hardin County |
| Area Code(s) | 641 |
| Timezone | Central Daylight Time (CDT) |
| Population (2022) | 528 |
| Population Growth Rate (2010-19) | 0.50% |
| Majority Ethnicity | White 99.26% |
| US Congressional District(s) | Iowa 4th |
| State House Districts | 49 |
| State Senate Districts | 25 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 99.26% |
| African American | 0% |
| Hispanic | 0% |
| Asian | 0.25% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0.49% |