Founded in 1825, Calhoun County is one of 102 counties in the state of Illinois. Historically, Calhoun County was formed from Pike County. The city of Hardin is the county seat. With FIPS code of 13, Calhoun County has a population of 4,369 and area of 253 square miles (655 km2).
List of all cities in Calhoun County, IL alphabetically
| City/Town | Postal Code | Area Code |
| Batchtown, IL | 62006 | 618/730 |
| Beechville, IL | 62006 | 618/730 |
| Brussels, IL | 62013 | 618/730 |
| Deer Plain, IL | 62013 | 618/730 |
| Gilead, IL | 62006 | 618/730 |
| Golden Eagle, IL | 62036 | 618/730 |
| Hamburg, IL | 62045 | 618/730 |
| Hardin, IL | 62047 | 618/730 |
| Kampsville, IL | 62053 | 618/730 |
| Meppen, IL | 62013 | 618/730 |
| Michael, IL | 62065 | 618/730 |
| Mozier, IL | 62070 | 618/730 |