Morgan County is a county located in the U.S. state of Illinois. According to the 2020 census, it had a population of 32,915. Its county seat is Jacksonville.

Jacksonville is a city in Morgan County, Illinois, United States. The population was 17,616 at the 2020 census, down from 19,446 in 2010. It is the county seat of Morgan County. It is home to Illinois College, Illinois School for the Deaf, and the Illinois School for the Visually Impaired. Jacksonville is the principal city of the Jacksonville Micropolitan Statistical Area, which includes all of Morgan and Scott counties.