There are 102 counties in the state of Illinois. Here they are listed in alphabetical order. You may also want to check out the map of Illinois.
- Adams County
- Alexander County
- Bond County
- Boone County
- Brown County
- Bureau County
- Calhoun County
- Carroll County
- Cass County
- Champaign County
- Christian County
- Clark County
- Clay County
- Clinton County
- Coles County
- Cook County
- Crawford County
- Cumberland County
- DeKalb County
- DeWitt County
- Douglas County
- DuPage County
- Edgar County
- Edwards County
- Effingham County
- Fayette County
- Ford County
- Franklin County
- Fulton County
- Gallatin County
- Greene County
- Grundy County
- Hamilton County
- Hancock County
- Hardin County
- Henderson County
- Henry County
- Iroquois County
- Jackson County
- Jasper County
- Jefferson County
- Jersey County
- Jo Daviess County
- Johnson County
- Kane County
- Kankakee County
- Kendall County
- Knox County
- Lake County
- LaSalle County
- Lawrence County
- Lee County
- Livingston County
- Logan County
- Macon County
- Macoupin County
- Madison County
- Marion County
- Marshall County
- Mason County
- Massac County
- McDonough County
- McHenry County
- McLean County
- Menard County
- Mercer County
- Monroe County
- Montgomery County
- Morgan County
- Moultrie County
- Ogle County
- Peoria County
- Perry County
- Piatt County
- Pike County
- Pope County
- Pulaski County
- Putnam County
- Randolph County
- Richland County
- Rock Island County
- St. Clair County
- Saline County
- Sangamon County
- Schuyler County
- Scott County
- Shelby County
- Stark County
- Stephenson County
- Tazewell County
- Union County
- Vermilion County
- Wabash County
- Warren County
- Washington County
- Wayne County
- White County
- Whiteside County
- Will County
- Williamson County
- Winnebago County
- Woodford County