| Place Name | Big Arm |
| Place Type | Census Designated Place |
| ZIP Code(s) | 59910 |
| County | Lake County |
| Area Code(s) | 406 |
| Timezone | Mountain Daylight Time (MDT) |
| Population (2022) | 287 |
| Population Growth Rate (2010-19) | 23.16% |
| Majority Ethnicity | Native American 0% |
| US Congressional District(s) | Montana At-Large |
| State House Districts | 12 |
| State Senate Districts | 6 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 26.83% |
| African American | 0% |
| Hispanic | 73.17% |
| Asian | 0% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 0% |