Places beginning with RO in Illinois, United States
- Roaches
- Roachtown
- Roanoke
- Roanoke, Township of
- Robbins
- Robbs
- Robein
- Robert Brooks Homes (subdivision)
- Roberts
- Roberts, Township of
- Robert Taylor Homes (subdivision)
- Robinson
- Robinson, Township of
- Robinwood
- Roby
- Rochelle
- Rochester
- Rochester
- Rochester, Township of
- Rock
- Rockbridge
- Rockbridge, Township of
- Rock City
- Rock Creek
- Rock Creek
- Rock Creek-Lima, Township of
- Rock Creek Number 12 Election Precinct
- Rock Creek, Township of
- Rockdale
- Rockdale Junction
- Rockefeller
- Rock Election Precinct
- Rock Falls
- Rockford
- Rockford, Township of
- Rock Grove
- Rock Grove, Township of
- Rock Island
- Rock Island County
- Rock Island, Township of
- Rockport
- Rock Run Park
- Rock Run, Township of
- Rockton
- Rockton, Township of
- Rockvale, Township of
- Rockville, Township of
- Rockwood
- Rockwood Election Precinct
- Rocky Run, Township of
- Rodden
- Rodemich
- Rodgersville
- Rogers Park (subdivision)
- Rogers, Township of
- Rohrer
- Roland
- Rolling Green
- Rolling Greens Mobile Home Park
- Rolling Meadows
- Rollins
- Rollo
- Rombury Oaks
- Rome
- Romeo
- Romeoville
- Rome, Township of
- Romine, Township of
- Rondout
- Roodhouse
- Roodhouse, Township of
- Rooks Creek
- Rooks Creek, Township of
- Roots
- Rosamond
- Rosamond, Township of
- Roscoe
- Roscoe, Township of
- Rosebud
- Rosecrans
- Rosedale
- Rosedale
- Rosedale, Township of
- Rosefield, Township of
- Rose Hill
- Rose Lake
- Roseland (subdivision)
- Roselle
- Rosemont
- Rosemont
- Rose, Township of
- Roseville
- Roseville, Township of
- Rosewood Heights
- Rosiclare
- Rosiclare Precinct
- Roslyn
- Ross, Township of
- Ross, Township of
- Ross, Township of
- Rossville
- Rossville Junction
- Roth
- Round Grove
- Round Grove, Township of
- Round Knob
- Round Lake
- Round Lake Beach
- Round Lake Heights
- Round Lake Park
- Round Prairie
- Rountree, Township of
- Rowe
- Rowell
- Roxana
- Roxbury
- Royal
- Royal Acres Trailer Park
- Royal Heights
- Royal Lake
- Royal Lake Resort
- Royalton
- Rozetta
- Rozetta, Township of