| Place Name | Old Monroe |
| Place Type | City |
| ZIP Code(s) | 63369 |
| County | Lincoln County |
| Area Code(s) | 636 |
| Timezone | Central Daylight Time (CDT) |
| Population (2022) | 269 |
| Population Growth Rate (2010-19) | -6.04% |
| Majority Ethnicity | White 100% |
| Metro/Micro Stats Area | St. Louis, MO-IL |
| US Congressional District(s) | Missouri 3rd |
| State House Districts | 64 |
| State Senate Districts | 10 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 100% |
| African American | 0% |
| Hispanic | 0% |
| Asian | 0% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0% |