Marshall is a city in Clark County, Illinois, United States, located about 20 miles (32 km) west of Terre Haute, Indiana. The population was 3,771 at the 2000 census. It is the county seat of Clark County.
Marshall is located at 39°23′34″N 87°41′37″W / 39.39278°N 87.69361°W / 39.39278; -87.69361 (39.392848, -87.693627).
According to the United States Census Bureau, the city has a total area of 3.2 square miles (8.2 km²), of which, 3.1 square miles (8.1 km²) of it is land and 0.32% is water.