| Place Name | Arnold |
| Place Type | City |
| ZIP Code(s) | 63010 |
| County | Jefferson County |
| Area Code(s) | 636,314 |
| Timezone | Central Daylight Time (CDT) |
| Population (2022) | 20,859 |
| Population Growth Rate (2010-19) | 0.24% |
| Majority Ethnicity | White 96.41% |
| Metro/Micro Stats Area | St. Louis, MO-IL |
| US Congressional District(s) | Missouri 2nd |
| State House Districts | 97,113 |
| State Senate Districts | 22 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 96.41% |
| African American | 0.4% |
| Hispanic | 0.09% |
| Asian | 0.63% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 2.47% |