Jacksonville is a city located in the state of Illinois in the United States. It serves as the county seat of Morgan County and functions as the principal city of the Jacksonville Micropolitan Statistical Area, which encompasses both Morgan and Scott counties.
The city had a population of 17,616 according to the 2020 census, reflecting a decrease from the 19,446 residents recorded in 2010. The area is notable for hosting several educational institutions, including Illinois College, the Illinois School for the Deaf, and the Illinois School for the Visually Impaired. MacMurray College was formerly located in the city.