Johnson County, county in Illinois, United States. As of 2020 county had an estimated population of 12,358 inhabitants. The county was created 212 years ago in 1812. Its county seat is Vienna.
There are 1 city/town in Johnson County, IL. The largest city of Johnson County is Vienna with a population of 1,427.
List of cities, towns, neighborhoods & other populated places in Johnson County.
City Name | Title | Population |
---|---|---|
Vienna | City in Johnson County, Illinois | 1,427 |