[2] The county was named for George Rogers Clark, an officer who served in the American Revolution.

At the time of its formation, Clark County included about a third of Illinois, and extended as far north as the present state of Wisconsin.

A county-wide referendum was held In 1839 to determine whether Auburn or Marshall would be designated as the new seat.

The North Fork of the Embarras River and Hurricane Creek are the main streams in western Clark County.

Other than the Wabash River, Big Creek is the major stream in the eastern part of the county.

[9] As of the 2010 United States census, there were 16,335 people, 6,782 households, and 4,593 families residing in the county.

[18] There are three school districts in Clark County (Marshall, Martinsville and Casey-Westfield) with a total enrollment (2004) of 3,014 students.