| Place Name | Green Grass |
| Place Type | Census Designated Place |
| ZIP Code(s) | 57625 |
| County | Dewey County |
| Area Code(s) | 605 |
| Timezone | Mountain Standard Time (MST) |
| Population (2022) | 31 |
| Population Growth Rate (2010-19) | -40.00% |
| Majority Ethnicity | Native American 0% |
| US Congressional District(s) | South Dakota At-Large |
| State House Districts | 28A |
| State Senate Districts | 28 |
| Race/Ethnicy | Percentage of Population (2018) |
|---|---|
| White | 0% |
| African American | 0% |
| Hispanic | 100% |
| Asian | 0% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0% |