Ontario
- County:
- Hand County
- County Seat:
- No
- Area (mi²):
- 35.68
- State:
- South Dakota
Ontario is located in Hand County, South Dakota. Ontario has a 2025 population of 23 . Ontario is currently declining at a rate of -4.17% annually and its population has decreased by -4.17% since the most recent census, which recorded a population of 24 in 2020.
The median age in Ontario is 39.8 years: 37.3 years for males, and 57 years for females. For every 100 females there are 230.0 males.