| Place Name | St. Mary Township |
| Place Type | Township |
| ZIP Code(s) | 62321 62367 |
| County | Hancock County |
| Area Code(s) | 309,217 |
| Timezone | Central Standard Time (CST) |
| Population (2021) | 692 |
| Majority Ethnicity | White 96.68% |
| Metro/Micro Stats Area | Fort Madison-Keokuk, IA-IL-MO |
| US Congressional District(s) | Illinois 18th |
| State House Districts | 94 |
| State Senate Districts | 47 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 96.68% |
| African American | 2.75% |
| Hispanic | 0% |
| Asian | 0% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0.58% |