Counties in Illinois
Illinois has 102 counties. They are listed by population, largest first, starting with Cook County, DuPage County, and Lake County.
- Cook County, Illinois
- DuPage County, Illinois
- Lake County, Illinois
- Will County, Illinois
- Kane County, Illinois
- McHenry County, Illinois
- Winnebago County, Illinois
- Madison County, Illinois
- St. Clair County, Illinois
- Champaign County, Illinois
- Sangamon County, Illinois
- Peoria County, Illinois
- McLean County, Illinois
- Kendall County, Illinois
- Rock Island County, Illinois
- Tazewell County, Illinois
- LaSalle County, Illinois
- Kankakee County, Illinois
- DeKalb County, Illinois
- Macon County, Illinois
- Vermilion County, Illinois
- Williamson County, Illinois
- Adams County, Illinois
- Whiteside County, Illinois
- Grundy County, Illinois
- Boone County, Illinois
- Jackson County, Illinois
- Ogle County, Illinois
- Henry County, Illinois
- Knox County, Illinois
- Coles County, Illinois
- Macoupin County, Illinois
- Stephenson County, Illinois
- Woodford County, Illinois
- Clinton County, Illinois
- Franklin County, Illinois
- Marion County, Illinois
- Jefferson County, Illinois
- Livingston County, Illinois
- Monroe County, Illinois
- Effingham County, Illinois
- Christian County, Illinois
- Lee County, Illinois
- Fulton County, Illinois
- Morgan County, Illinois
- Bureau County, Illinois
- Randolph County, Illinois
- Montgomery County, Illinois
- Logan County, Illinois
- Iroquois County, Illinois
- McDonough County, Illinois
- Saline County, Illinois
- Jo Daviess County, Illinois
- Jersey County, Illinois
- Fayette County, Illinois
- Shelby County, Illinois
- Perry County, Illinois
- Douglas County, Illinois
- Crawford County, Illinois
- Bond County, Illinois
- Hancock County, Illinois
- Piatt County, Illinois
- Union County, Illinois
- Edgar County, Illinois
- Warren County, Illinois
- Wayne County, Illinois
- Carroll County, Illinois
- Mercer County, Illinois
- Richland County, Illinois
- De Witt County, Illinois
- Clark County, Illinois
- Moultrie County, Illinois
- Pike County, Illinois
- Lawrence County, Illinois
- Washington County, Illinois
- Massac County, Illinois
- Johnson County, Illinois
- White County, Illinois
- Ford County, Illinois
- Clay County, Illinois
- Cass County, Illinois
- Mason County, Illinois
- Menard County, Illinois
- Marshall County, Illinois
- Greene County, Illinois
- Wabash County, Illinois
- Cumberland County, Illinois
- Jasper County, Illinois
- Hamilton County, Illinois
- Schuyler County, Illinois
- Brown County, Illinois
- Henderson County, Illinois
- Edwards County, Illinois
- Putnam County, Illinois
- Stark County, Illinois
- Scott County, Illinois
- Pulaski County, Illinois
- Gallatin County, Illinois
- Alexander County, Illinois
- Calhoun County, Illinois
- Pope County, Illinois
- Hardin County, Illinois