Places beginning with FO in Illinois, United States
- Fogarty
- Fond du Lac
- Fondulac Plaza Shopping Center
- Fondulac, Township of
- Foosland
- Fopal
- Ford County
- Ford Heights
- Forest City
- Forest City, Township of
- Forest Green Lake Estates (subdivision)
- Forest Hills
- Forest Hill (subdivision)
- Forest Homes
- Forest Lake
- Forest Park
- Forest Park
- Forest River
- Forest View
- Forestville (subdivision)
- Forman
- Formosa Junction
- Forrest
- Forreston
- Forreston, Township of
- Forrest, Township of
- Forsyth
- Fort Dearborn Addition (subdivision)
- Fort Gage
- Fort Hill
- Fort Russell, Township of
- Forty Acres
- Fossland
- Fosterburg
- Foster Pond (historical)
- Foster, Township of
- Foster, Township of
- Fountain
- Fountain Bluff, Township of
- Fountain Creek
- Fountain Creek, Township of
- Fountain Gap
- Fountain Green
- Fountain Green, Township of
- Four Corners
- Four Mile, Township of
- Fowler
- Fox
- Foxborough Estates (subdivision)
- Fox Chase Estates
- Foxcroft
- Foxcroft (subdivision)
- Foxfield
- Fox Hills
- Fox Lake
- Fox Lake Hills
- Fox Point North (subdivision)
- Fox River Estates
- Fox River Grove
- Fox River Heights
- Fox River Shores
- Fox Run (subdivision)
- Fox, Township of
- Fox, Township of
- Foxville