Places beginning with CO in Illinois, United States
- Coal City
- Coaler
- Coal Hollow
- Coalton
- Coalton
- Coal Valley
- Coal Valley, Township of
- Coalville
- Coatsburg
- Cobden
- Cobden District Number 1 Election Precinct
- Cobden District Number 2 Election Precinct
- Cody
- Coello
- Coe, Township of
- Coffee Election Precinct
- Coffeen
- Colby Point
- Colchester
- Colchester, Township of
- Coldbrook
- Coldbrook, Township of
- Cold Spring, Township of
- Coleman
- Coleman
- Coles
- Coles County
- Coleta
- Colfax
- Colfax, Township of
- Collins
- Collins (historical)
- Collinsville
- Collinsville, Township of
- Collison
- Colmar
- Coloma, Township of
- Colona
- Colona, Township of
- Colonial Gardens (subdivision)
- Colonial Gardens (subdivision)
- Colonial Meadows
- Colp
- Columbia
- Columbiana (historical)
- Columbus
- Columbus (historical)
- Columbus, Township of
- Colusa
- Colvin Park
- Combs
- Comer
- Commanche Village
- Como
- Compro
- Compromise, Township of
- Compton
- Compton Election Precinct
- Conant
- Concord
- Concord Election Precinct
- Concord, Township of
- Concord, Township of
- Concord, Township of
- Condit, Township of
- Confidence
- Congerville
- Conleys Patch (subdivision)
- Conlogue
- Conover
- Conrad
- Conwayville (historical)
- Cook County
- Cookes Subdivision
- Cooks Mills
- Cooksville
- Cooper
- Cooperstown
- Cooperstown, Township of
- Cooper, Township of
- Copley, Township of
- Copperfield (subdivision)
- Cora
- Coral
- Coral, Township of
- Cordes
- Cordova
- Cordova, Township of
- Coreys Bluff (subdivision)
- Corinth
- Cornell
- Cornell (subdivision)
- Cornerville
- Cornland
- Cornwall, Township of
- Cortland
- Cortland, Township of
- Corwin, Township of
- Corwith (subdivision)
- Cottage Grove
- Cottage Hills
- Cottage, Township of
- Cotton Hill
- Cotton Hill, Township of
- Cottonwood
- Cottonwood, Township of
- Coughlin
- Coulterville
- Coulterville Election Precinct
- Council Hill
- Council Hill, Township of
- Country Acres Mobile Home Park
- Country Club Estates
- Country Club Estates (subdivision)
- Country Club Hills
- Country Meadows
- Countryside
- Countryside East (subdivision)
- Countryside (subdivision)
- Countryside West (subdivision)
- Covell
- Coventry Creek (subdivision)
- Coventry Hills East (subdivision)
- Coventry Hills (subdivision)
- Covington
- Covington
- Covington, Township of
- Cowden
- Cowling
- Coyne
- Coyne Center
- Coynes