Clark County, Illinois

county in Illinois, United States

Clark County is a county in the southeastern part of U.S. state of Illinois, along the Indiana state line. As of the 2020 census, the population was 15,455.[1] The county seat is Marshall.[2] The county was founded in 1819 and named for George Rogers Clark, an officer who served in the American Revolutionary War.[3]


  1. "QuickFacts: Clark County, Illinois". United States Census Bureau. Retrieved August 11, 2023.
  2. "Find a County". National Association of Counties. Archived from the original on 2011-05-31. Retrieved 2011-06-07.
  3. Perrin, p. 237