Marshall
- County:
- Clark County
- County Seat:
- Yes
- Area (mi²):
- 3.668
- State:
- Illinois
Marshall is a city located in Clark County, Illinois. Marshall has a 2026 population of 3,865. It is also the county seat of Clark County. Marshall is currently declining at a rate of -1% annually and its population has decreased by -2.18% since the most recent census, which recorded a population of 3,951 in 2020.