Auburn
- County:
- Sangamon County
- County Seat:
- No
- Area (mi²):
- 4.124
- State:
- Illinois
Auburn is a city located in Sangamon County, Illinois. Auburn has a 2026 population of 4,453. Auburn is currently declining at a rate of -0.18% annually and its population has decreased by -2.05% since the most recent census, which recorded a population of 4,546 in 2020.