
Marseilles
- County:
- LaSalle County
- County Seat:
- No
- Area (mi²):
- 9.049
- State:
- Illinois
Marseilles is a city located in LaSalle County, Illinois. Marseilles has a 2025 population of 4,741. Marseilles is currently declining at a rate of -0.34% annually and its population has decreased by -1.64% since the most recent census, which recorded a population of 4,820 in 2020.
The average household income in Marseilles is $77,436 with a poverty rate of 16.57%. The median age in Marseilles is 41 years: 40.5 years for males, and 41.2 years for females.