Most marked county highways in Clinton County are 2 lane paved roads. The ones that are not 2 lane paved are marked with an asterisk (*).

2: Keysport to County Highway 15.

3: Ferrin to Clinton/Fayette County Line

4: Hoffman to US 50

5: IL 161 to US 50

6*: Bartelso to Beckemeyer

7: Germantown to Breese

8: IL 160 to Aviston via Damisville and Albers. This route also extends south to I-64.

9*: County Highway 13 to IL 127.

11*: Jamestown to Breese

12*: St. Rose to County Highway 11.

13: Bond/Clinton County Line to Old US 50.

14: Madison/Clinton County Line to Old US 50.

15*: IL 127 to County Highway 2.

16: Clinton/Washington County Line to IL 161.

17*: County Highway 13 to IL 127.

18*: Clinton/Washington County Line to IL 161.

19: US 50 to County Highway 3.

20: IL 127 to County Highway 15.