DeWitt County is a county located in the U.S. state of Illinois. As of the 2020 census, the population was 15,516. Its county seat is Clinton. The county was formed on March 1, 1839, from Macon and McLean counties. The county was named in honor of the seventh Governor of New York State, DeWitt Clinton.

Macon County is a county located in the U.S. state of Illinois. According to the 2020 United States Census, it had a population of 103,998. Its county seat and most populous city is Decatur.