
Eureka
- County:
- Woodford County
- County Seat:
- No
- Area (mi²):
- 2.737
- State:
- Illinois
Eureka is a city located in Woodford County, Illinois. Eureka has a 2025 population of 5,166. Eureka is currently declining at a rate of -0.19% annually and its population has decreased by -0.96% since the most recent census, which recorded a population of 5,216 in 2020.
The average household income in Eureka is $72,759 with a poverty rate of 13.94%. The median age in Eureka is 40.7 years: 36.2 years for males, and 49.9 years for females.