Swan township
- County:
- Warren County
- County Seat:
- No
- Area (mi²):
- 35.311
- State:
- Illinois
Swan township is located in Warren County, Illinois. Swan township has a 2026 population of 231. Swan township is currently declining at a rate of -0.86% annually and its population has decreased by -4.15% since the most recent census, which recorded a population of 241 in 2020.
The median age in Swan township is 39.4 years: 39.5 years for males, and 39.3 years for females. For every 100 females there are 265.1 males.