A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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| Place Name | County | Place Type | Post Office Dates | More Information |
| Oak | Jefferson | Lost Town | 1891-1895 | |
| Oak City | Seward | Lost Town | Vacated 1897. | |
| Oak Grove | Pottawatomie | Lost Town | ||
| Oak Mills | Atchison | Lost Town | 1868-1945 | Oak Mills, Kansas, was once located along the Missouri River. The site was originally home to a Kanza Indian village. |
| Oak Ridge | Douglas | Lost Town | None | Jonathan F. Morgan and Governor Charles Robinson were the first to settle in Oak Ridge in about 1866. |
| Oakdale | Reno | Lost Town | Located January 22, 1889. | |
| Oakland | Jewell | Lost Town | ||
| Oakland | Montgomery | Paper Town | A paper town. | |
| Oakridge | Elk | Lost Town | Discontinued 1882. | |
| Oakwood | Linn | Lost Town | 1858-1905 | Once situated in the western portion of the county about ten miles northwest of Mound City. |
| Oasis | Logan | Lost Town | 1890 | This post office just a few short months. |
| Oasis | Saline | Lost Town | ||
| O’Brien Ferry | Doniphan | Lost Place | NA | Established 1861-62 on the Missouri River at Belmont. |
| Ocena, Oceana | Atchison | Lost Town | 1855-1858 | The post office moved to Pardee in August 1858. |
| Ocheltree | Johnson | Lost Town | 1869-1954 | A village in the extreme southern part of Johnson County. |
| Ocoee | Reno | Lost Town | Established 1879. | |
| Odee | Kingman | Lost Town | ||
| Odell | Harper | Lost Town | ||
| Odell | Sheridan | Lost Town | ||
| Odessa | Jewell | Lost Town | ||
| Og | Reno | Lost Town | ||
| Ohio | Smith | Lost Town | ||
| Ohio Center | Sedgwick | Lost Town | ||
| Ohio City | Edwards | Lost Town | Vacated 1897. | |
| Ohio City | Franklin | Lost Town | See Bowling Green. | |
| Ohio City | Marshall | Lost Town | Established 1855. | |
| Ohio Grove | Ottawa | Lost Town | ||
| Oil City | Butler | Lost Town | ||
| Oketo Ferry | Marshall | Lost Place | Operated 1859-67 on Big Blue River; Poor, Whitehead & Co., Proprietors. Located a half-mile south of Oketo. | |
| Olanthe | Johnson | Lost Town | Incorporated 1857. | |
| Olanthus | Norton | Lost Town | ||
| Olcott | Reno | Lost Town | Vacated 1903. | |
| “Old” Ogallah | Trego | Lost Town | See Park’s Fort. | |
| Old Ulysses | Grant | Lost Town | The site moved about 1899. The next site was called New Ulysses for a time. | |
| Ole, Middleton | Jefferson | Lost Town | 1857-1865 | The town’s name was changed from Middleton to Ole in 1860. |
| Olene | Graham | Lost Town | ||
| Olney | Rush | Lost Town | ||
| Omaha | Kearny | Lost Town | 1888 | Located about 1888. |
| Omio | Jewell | Lost Town | Vacated 1897. | |
| Omnia | Cloud | Lost Town | ||
| 110 Station | Osage | Name Change | Name changed to Richardson. | |
| Onion Creek | Osage | Lost Town | ||
| Ontario | Nemaha | Lost Town | 1862-1922 | It was located on the Northwestern Railroad. |
| Orbitello | Lincoln | Lost Town | ||
| Orchard/Coonsville | Linn | Lost Town | 1879-1885 | Situated on Sugar Creek about ten miles east of La Cygne. |
| Ord | Neosho | Lost Town | ||
| Oread | Coffey | Lost Town | ||
| Oregon | Jefferson | Lost Town | 1882-1883 1885 |
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| Orel | Allen | Lost Town | ||
| Orie | Sumner | Lost Town | ||
| Orino | Jewell | Lost Town | ||
| Oriole | Smith | Lost Town | ||
| Orion | Cloud | Lost Town | Same as Arion. | |
| Orleans | Lyon | Lost Town | ||
| Oro | Butler | Name Change | Name changed to Fulton. | |
| Orworth | Lincoln | Lost Town | ||
| Osage, Osage City | Bourbon | Lost Town | ||
| Osage | Miami | Lost Town | ||
| Osage Center | Osage | Name Change | Now Lyndon. | |
| Osage County | Osage | Current County | NA | One of the original 36 counties created in 1855. First called Weller County. Lyndon is the county seat. |
| Osage Mission | Neosho | Name Change | Now St. Paul. See Catholic Mission. | |
| Osawkie | Jefferson | Name Change | Now Ozawkie. | |
| Osborn | Crawford | Lost Town | 1867-1872 | |
| Osborn | Neosho | Lost Town | ||
| Osborne County | Osborne | Osborne | Created from unorganized area in 1867. Osborne is the county seat. | |
| Oswell | Rush | Lost Town | ||
| Ottawa County | Ottawa | Current County | NA | Created from unorganized area in 1860. Minneapolis is the county seat. |
| Otter Creek | Clay | Lost Town | ||
| Otter Lake | Pottawatomie | Lost Town | ||
| Otterborn, Otterbound | Sheridan | Lost Town | ||
| Otto | Marshall | Lost Town | Chartered 1858. | |
| Our Carter | Stafford | Lost Town | ||
| Over Muncha | Ellis | Lost Town | 1880 | The post office was only open for five months. |
| Overton | Butler | Lost Town | ||
| Oxford | Johnson | Lost Town | None | Once located in Oxford Township, adjoining New Santa Fe, Missouri, on the Santa Fe Trail. |
| Oxide | Ellsworth | Lost Town | 1883-1888 | |
| Oyer | Rooks | Lost Town | ||
| Ozark | Anderson | Lost Town | ||
| Ozro, Osrow Falls | Chautauqua | Lost Town | ||
| Ozro Falls | Jefferson | Lost Town |