Day County's 2026 population is estimated at 5,334, reflecting a -0.69% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Day County is the 33rd largest county in South Dakota. The 2010 population was 5,710 and has grown -6.58% since 2010.
Data after 2023 is projected based on recent change
Overall: 44.8 years
Female: 43.8 years
Male: 45.5 years
There are 4,220 adults, (1,449 of whom are seniors) in Day County.
Female: 2,722 (50.1%)
Male: 2,715 (49.9%)
The racial composition of Day County includes 84.09% White, 9.82% Native American, and smaller percentages for other race, Asian, Black or African American and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 4,572 | 84.09% |
| Native American | 534 | 9.82% |
| Two or more races | 316 | 5.81% |
| Other race | 9 | 0.17% |
| Asian | 4 | 0.07% |
| Black or African American | 2 | 0.04% |
Day County 's average per capita income is $46,046. Household income levels show a median of $66,033. The poverty rate stands at 14.82%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $99,211 | - |
| Families | $90,625 | $105,334 |
| Households | $66,033 | $91,552 |
| Non Families | $40,449 | $67,348 |
Average Income
Median Household Income
Poverty Rate