| Place Name | Janesville |
| Place Type | City |
| ZIP Code(s) | 50647 |
| County | Bremer County |
| Area Code(s) | 319 |
| Timezone | Central Standard Time (CST) |
| Population (2022) | 986 |
| Population Growth Rate (2010-19) | 11.18% |
| Majority Ethnicity | White 98.78% |
| Metro/Micro Stats Area | Waterloo-Cedar Falls, IA |
| US Congressional District(s) | Iowa 1st |
| State House Districts | 63 |
| State Senate Districts | 32 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 98.78% |
| African American | 0% |
| Hispanic | 0% |
| Asian | 0% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 1.22% |