| County |
Ogemaw County, MI |
Michigan |
| County |
Ogle County, IL |
Illinois |
| County |
Oglethorpe County, GA |
Georgia |
| City or Town |
Oglethorpe, GA |
Macon County, GA |
| State or Province |
Ohio |
United States of America |
| County |
Ohio County, IN |
Indiana |
| County |
Ohio County, KY |
Kentucky |
| County |
Ohio County, VA |
Virginia |
| County |
Ohio County, WV |
West Virginia |
| Rivers/Waterways |
Ohio River |
United States of America |
| Region |
Ohio River Valley |
United States of America |
| Location or Site |
Ohio State Capitol, Columbus, OH |
Columbus, OH |
| City or Town |
Oil Creek, PA |
Crawford County, PA |
| State or Province |
Oklahoma |
United States of America |
| City or Town |
Oklahoma City, OK |
Oklahoma County, OK |
| Location or Site |
Oklahoma County, OK |
Oklahoma |
| City or Town |
Okolona, MS |
Chickasaw County, MS |
| County |
Oktibbeha County, MS |
Mississippi |
| City or Town |
Old Brighton, PA |
Beaver County, PA |
| Location or Site |
Old City Cemetery, Nashville, TN |
Nashville, TN |
| Location or Site |
Old Louisville Cemetery, Louisville, GA |
Louisville, GA |
| Location or Site |
Old Market House, Carlisle, PA |
Carlisle, PA |
| Location or Site |
Old Negro Cemetery, Middletown, PA |
Middletown, PA |
| Location or Site |
Old Penitentiary, Washington D.C. |
Washington Arsenal, Washington, DC |
| Location or Site |
Old West, Dickinson College, Carlisle, PA |
Dickinson College |
| County |
Oldham County, KY |
Kentucky |
| County |
Oldham County, TX |
Texas |
| County |
Olmstead County, MN |
Minnesota |
| City or Town |
Olney, IL |
Richland County, IL |
| City or Town |
Omaha, NE |
Douglas County, NE |
