South Otter township
- County:
- Macoupin County
- County Seat:
- No
- Area (mi²):
- 35.751
- State:
- Illinois
South Otter township is located in Macoupin County, Illinois. South Otter township has a 2026 population of 442. South Otter township is currently declining at a rate of -0.67% annually and its population has decreased by -2.21% since the most recent census, which recorded a population of 452 in 2020.
The median household income in South Otter township is $73,750 with a poverty rate of 4.82%. The median age in South Otter township is 49 years: 61 years for males, and 48.3 years for females. For every 100 females there are 115.8 males.