Seneca
- County:
- Faulk County
- County Seat:
- No
- Area (mi²):
- 0.419
- State:
- South Dakota
Seneca is a town located in Faulk County, South Dakota. Seneca has a 2026 population of 23. Seneca is currently declining at a rate of 0% annually and its population has increased by 4.55% since the most recent census, which recorded a population of 22 in 2020.
The median age in Seneca is 67.3 years: 57.9 years for males, and 70.8 years for females. For every 100 females there are 214.3 males.