ILGenWeb References

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Name (& Source)	County	Notes/aka/twp
O'Fallon^{1, 2}	St. Clair	.
Oak^{1, 2}	Pope	.
Oak Brook²	DuPage	.
Oak Forest²	Cook	.
Oak Grove²	Lake	.
Oak Grove^{1, 2}	McLean	.
Oak Grove²	Rock Island	.
Oak Hill^{1, 2}	Peoria	.
Oak Hills²	St. Clair	.
Oak Lawn^{1, 2}	Cook	.
Oak Openings²	Kane	.
Oak Park^{1, 2}	Cook	.
Oak Point^{1, 2}	Clark	.
Oak Ridge²	Woodford	.
Oak Run²	Knox	.
Oakbrook Terrace²	DuPage	.
Oakcrest²	Clark	.
Oakdale^{1, 2}	Washington	.
Oakford^{1, 2}	Menard	.
Oakglen^{1, 2}	Cook	.
Oakland^{1, 2, 5}	Coles	formerly known as Cleaverville¹¹
Oakland Center²	Schuyler	.
Oakley^{1, 2}	Macon	.
Oakton²	Cook	.
Oaktown¹	Pulaski	.
Oakwood^{1, 2}	Vermilion	.
Oakwood Heights²	Madison	.
Oakwood Hills²	McHenry	.
Obed^{1, 2}	Shelby	.
Oblong^{1, 2}	Crawford	.
Oconee^{1, 2}	Shelby	.
Ocoya (Ocova)^{1, 2}	Livingston	.
Odell^{1, 2}	Livingston	.
Odgen²	Wabash	.
Odin^{1, 2}	Marion	.
Ogden^{1, 2, 6}	Champaign	.
Ogle^{1, 2}	Mercer	.
Ogles^{1, 2}	St. Clair	.
Oglesby^{1, 2}	La Salle	.
Ohio^{1, 2}	Bureau	.
Ohlman^{1, 2}	Montgomery	.
Oil Center²	Crawford	.
Oil Grove²	Crawford	.
Oilfield²	Clark	.
Okau⁵	Washington	post office
Okau Settlement⁵	Macon	.
Okawville^{1, 2}	Washington	.
Oklahoma²	Kankakee	historical
Old Brownfield²	Pope	.
Old Dad⁵	Putnam	aka Dad Joe's Grove
Old Du Quoin²	Perry	.
Old Gilchrist²	Mercer	.
Old Kane²	Greene	.
Old Kaskaskia²	Randolph	.
Old Marissa²	St. Clair	.
Old Mazon^U	Grundy	aka Mazon
Old Mill Creek²	Lake	.
Old Niota²	Hancock	.
Old Owaneco²	Christian	.
Old Pearl²	Pike	.
Old Princeton²	Cass	.
Old Ripley^{1, 2}	Bond	founded by the Wheelock brothers¹⁵
Old Ripley Township¹⁶	Bond	.
Old Salem Chautauqua²	Menard	.
Old Shawneetown²	Gallatin	.
Old Stonington²	Christian	.
Oldenburg²	Madison	.
Oldtown²	Saline	.
Olena^{1, 2}	Henderson	.
Olga^{1, 2}	Hamilton	.
Olin²	Peoria	.
Olive Branch^{1, 2}	Alexander	.
Oliver^{1, 2}	Edgar	.
Oliver²	Whiteside	.
Olivet²	Vermilion	.
Olmsted^{1, 2}	Pulaski	.
Olmsted's Mound⁵	Morgan	.
Olney^{1, 2}	Richland	.
Olympia Fields²	Cook	.
Omaha^{1, 2}	Gallatin	.
Omar²	Johnson	.
Omega^{1, 2}	Marion	.
Onarga^{1, 2}	Iroquois	.
Oneco^{1, 2}	Stephenson	.
Oneida^{1, 2}	Knox	.
Ono⁵	Edgar	post office⁵
Ontario^{1, 2}	Knox	.
Ontarioville^{1, 2}	DuPage	.
Opa⁷	Peoria	as called by French; west side of Peoria Lake; principal village of Peoria Indians
Opdyke^{1, 2}	Jefferson	.
Ophiem^{1, 2}	Henry	.
Oquawka^{1, 2}	Henderson	.
Ora¹	Jackson	.
Oran^U	Logan	.
Orange^{1, 2}	Clark	.
Orange Prairie^{1, 2}	Peoria	.
Orangemans Hall²	Mercer	.
Orangeville^{1, 2}	Stephenson	.
Oraville^{1, 2}	Jackson	.
Orchard Mines¹	Peoria	.
Orchardville^{1, 2}	Wayne	.
Oreana^{1, 2}	Macon	.
Oregon^{1, 2}	Ogle	aka Oregon City⁵
Orendorff's Mill & Settlement⁵	Tazewell	.
Orient²	Franklin	.
Orio²	Wabash	.
Orion^{1, 2}	Henry	.
Orland Hills^{1, 2}	Cook	.
Orland Park^{1, 2}	Cook	.
Orleans^{1, 2}	Morgan	.
Ormonde^{1, 2}	Warren	.
Orndorff^U	Logan	.
Orvil^U	Logan	.
Osage¹	Franklin	.
Osbernville²	Christian	Mosquito twp
Osborn^{1, 2}	Rock Island	.
Osceola^{1, 2}	Stark	Elmira twp
Osco^{1, 2}	Henry	.
Oskaloosa^{1, 2}	Clay	.
Osman^{1, 2}	McLean	.
Ospur^{1, 2}	DeWitt	.
Oswego^{1, 2}	Kendall	.
Ottawa^{1, 2, 5}	La Salle	.
Otter^{1, 2}	La Salle	historical
Otterville^{1, 2}	Jersey	.
Otto²	Fulton	historical
Otto^{1, 2}	Kankakee	.
Ottville²	Bureau	.
Out House Settlement⁵	Clinton	.
Ovid³	Jackson	1823 Gazetteer
Owaneco^{1, 2}	Christian	aka Locust; post office⁶
Owen Center^{1, 2}	Winnebago	.
Ox Bo¹	Putnam	.
Oxford³	Hamilton	1823 Gazetteer
Oxford²	Henry	historical
Oxville^{1, 2}	Scott	.
Ozark^{1, 2}	Johnson	.

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